Positioning and stabilising structure and patient interface

ABSTRACT

A patient interface for delivery of a supply of pressurised air or breathable gas to an entrance of a patient&#39;s airways comprising: a cushion member that includes a retaining structure and a seal-forming structure permanently connected to the retaining structure; a frame member attachable to the retaining structure; and a positioning and stabilising structure attachable to the frame member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/417,610, filed Jan. 27, 2015, now allowed, which is the U.S. nationalphase of International Application No. PCT/AU2013/000830 filed 26 Jul.2013 which designated the U.S. and claims the benefit of US ProvisionalAppln. Nos. 61/676,456, filed Jul. 27, 2012, 61/817,674, filed Apr. 30,2013, 61/823,192, filed May 14, 2013, 61/837,521, filed Jun. 20, 2013,and 61/839,916, filed Jun. 27, 2013. This application claims the benefitof Australian Provisional Appln. Nos. 2012903504, filed Aug. 15, 2012,2012904378, filed Oct. 8, 2012, 2013900132, filed Jan. 16, 2013,2013900133, filed Jan. 16, 2013, 2013902305, filed Jun. 24, 2013, and2013900168, filed Jan. 18, 2013. This application claims the benefit ofNew Zealand Appln. Nos. 605907, filed Jan. 16, 2013, 610823, filed May21, 2013 and 605908, filed Jan. 16, 2013. Each of the applicationsreferenced above is incorporated herein by reference in its entirety.

A portion of the disclosure of this patent document contains materialwith is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appear in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE TECHNOLOGY (1) Field of the Technology

The present technology relates to one or more of the diagnosis,treatment and amelioration of respiratory disorders, and to proceduresto prevent respiratory disorders. In particular, the present technologyrelates to medical devices, and their use for treating respiratorydisorders and for preventing respiratory disorders.

(2) Description of the Related Art

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways include a series of branching tubes, which become narrower,shorter and more numerous as they penetrate deeper into the lung. Theprime function of the lungs is gas exchange, allowing oxygen to movefrom the air into the venous blood and carbon dioxide to move out. Thetrachea divides into right and left main bronchi, which further divideeventually into terminal bronchioles. The bronchi make up the conductingairways, and do not take part in gas exchange. Further divisions of theairways lead to the respiratory bronchioles, and eventually to thealveoli. The alveolated region of the lung is where the gas exchangetakes place, and is referred to as the respiratory zone.

A range of respiratory disorders exist.

Obstructive Sleep Apnoea (OSA), a form of Sleep Disordered Breathing(SDB), is characterized by occlusion of the upper air passage duringsleep. It results from a combination of an abnormally small upper airwayand the normal loss of muscle tone in the region of the tongue, softpalate and posterior oropharyngeal wall during sleep. The conditioncauses the affected patient to stop breathing for periods typically of30 to 120 seconds duration, sometimes 200 to 300 times per night. Itoften causes excessive daytime somnolence, and it may causecardiovascular disease and brain damage. The syndrome is a commondisorder, particularly in middle aged overweight males, although aperson affected may have no awareness of the problem. See U.S. Pat. No.4,944,310 (Sullivan).

Cheyne-Stokes Respiration (CSR) is a disorder of a patient's respiratorycontroller in which there are rhythmic alternating periods of waxing andwaning ventilation, causing repetitive de-oxygenation and re-oxygenationof the arterial blood. It is possible that CSR is harmful because of therepetitive hypoxia. In some patients CSR is associated with repetitivearousal from sleep, which causes severe sleep disruption, increasedsympathetic activity, and increased afterload. See U.S. Pat. No.6,532,959 (Berthon-Jones).

Obesity Hyperventilation Syndrome (OHS) is defined as the combination ofsevere obesity and awake chronic hypercapnia, in the absence of otherknown causes for hypoventilation. Symptoms include dyspnea, morningheadache and excessive daytime sleepiness.

Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a groupof lower airway diseases that have certain characteristics in common.These include increased resistance to air movement, extended expiratoryphase of respiration, and loss of the normal elasticity of the lung.Examples of COPD are emphysema and chronic bronchitis. COPD is caused bychronic tobacco smoking (primary risk factor), occupational exposures,air pollution and genetic factors. Symptoms include: dyspnea onexertion, chronic cough and sputum production.

Neuromuscular Disease (NMD) is a broad term that encompasses manydiseases and ailments that impair the functioning of the muscles eitherdirectly via intrinsic muscle pathology, or indirectly via nervepathology. Some NMD patients are characterised by progressive muscularimpairment leading to loss of ambulation, being wheelchair-bound,swallowing difficulties, respiratory muscle weakness and, eventually,death from respiratory failure. Neuromuscular disorders can be dividedinto rapidly progressive and slowly progressive: (i) Rapidly progressivedisorders: Characterised by muscle impairment that worsens over monthsand results in death within a few years (e.g. Amyotrophic lateralsclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers);(ii) Variable or slowly progressive disorders: Characterised by muscleimpairment that worsens over years and only mildly reduces lifeexpectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic musculardystrophy). Symptoms of respiratory failure in NMD include: increasinggeneralised weakness, dysphagia, dyspnea on exertion and at rest,fatigue, sleepiness, morning headache, and difficulties withconcentration and mood changes.

Chest wall disorders are a group of thoracic deformities that result ininefficient coupling between the respiratory muscles and the thoraciccage. The disorders are usually characterised by a restrictive defectand share the potential of long term hypercapnic respiratory failure.Scoliosis and/or kyphoscoliosis may cause severe respiratory failure.Symptoms of respiratory failure include: dyspnea on exertion, peripheraloedema, orthopnoea, repeated chest infections, morning headaches,fatigue, poor sleep quality and loss of appetite.

Otherwise healthy individuals may take advantage of systems and devicesto prevent respiratory disorders from arising.

Systems

One known product used for treating SDB is the S9 Sleep Therapy System,manufactured by ResMed.

Therapy

Nasal Continuous Positive Airway Pressure (CPAP) therapy has been usedto treat Obstructive Sleep Apnea (OSA). The hypothesis is thatcontinuous positive airway pressure acts as a pneumatic splint and mayprevent upper airway occlusion by pushing the soft palate and tongueforward and away from the posterior oropharyngeal wall.

Non-invasive ventilation (NIV) has been used to treat OHS, COPD, MD andChest Wall disorders.

Patient Interface

The application of a supply of air at positive pressure to the entranceof the airways of a patient is facilitated by the use of a patientinterface, such as a nasal mask, full-face mask or nasal pillows. Afull-face mask includes a mask with one sealing-forming portion coveringat least the nares and mouth, or more than one sealing-forming portionto individually cover at least the nares and mouth. A range of patientinterface devices are known, however a number of them suffer from beingone or more of obtrusive, aesthetically undesirable, poorly fitting,difficult to use and uncomfortable especially when worn for long periodsof time or when a patient is unfamiliar with a system. Masks designedsolely for aviators, as part of personal protection equipment or for theadministration of anaesthetics may be tolerable for their originalapplication, but nevertheless be undesirably uncomfortable to be wornfor extended periods, for example, while sleeping.

Seal-Forming Structure

Patient interfaces typically include a seal-forming structure.

One type of seal-forming structure extends around the periphery of thepatient interface, and is intended to seal against the user's face whenforce is applied to the patient interface with the seal-formingstructure in confronting engagement with the user's face. Theseal-forming structure may include an air or fluid filled cushion, or amoulded or formed surface of a resilient seal element made of anelastomer such as a rubber. With this type of seal-forming structure, ifthe fit is not adequate, there will be gaps between the seal-formingstructure and the face, and additional force will be required to forcethe patient interface against the face in order to achieve a seal.

Another type of seal-forming structure incorporates a flap seal of thinmaterial so positioned about the periphery of the mask so as to providea self-sealing action against the face of the user when positivepressure is applied within the mask. Like the previous style ofseal-forming structure, if the match between the face and the mask isnot good, additional force may be required to effect a seal, or the maskmay leak. Furthermore, if the shape of the seal-forming structure doesnot match that of the patient, it may crease or buckle in use, givingrise to leaks.

Another form of seal-forming structure may use adhesive to effect aseal. Some patients may find it inconvenient to constantly apply andremove an adhesive to their face.

A range of patient interface seal-forming structure technologies aredisclosed in the following patent applications, assigned to ResMedLimited: WO 1998/004,310; WO 2006/074,513; WO 2010/135,785.

Positioning and Stabilising

A seal-forming structure of a patient interface used for positive airpressure therapy is subject to the corresponding force of the airpressure to disrupt a seal. Thus a variety of techniques have been usedto position the seal-forming structure, and to maintain it in sealingrelation with the appropriate portion of the face.

One technique is the use of adhesives. See for example US Patentpublication US 2010/0000534.

Another technique is the use of one or more straps and stabilisingharnesses. Many such harnesses suffer from being one or more ofill-fitting, bulky, uncomfortable and awkward to use.

Rigid elements, also known as “rigidisers”, have been used withstretchable headgears previously. One known problem is associated withthe fact that a rigidiser permanently attached (e.g. laminated orstitched) to a large area of the stretchable material limits thestretchable length of the material, thus affecting the elasticproperties of the entire headgear. Another issue concerns cleaning theheadgear which would require both the rigidiser and stretchable materialto be washed together as they are permanently attached to each other.

Vent Technologies

Some forms of patient interface systems may include a vent to allow thewashout of exhaled carbon dioxide. Many such vents are noisy. Others mayblock in use and provide insufficient washout. Some vents may bedisruptive of the sleep of a bed-partner of the patient, e.g. throughnoise or focussed airflow. Some vents cannot be properly cleaned andmust be discarded after they become blocked. Some vents are intended tobe used for a short duration of time, i.e. less than three months, andtherefore are manufactured from fragile material to prevent washing orfrequent washing so as to encourage more frequent replacement of thevent.

ResMed Limited has developed a number of improved mask venttechnologies. See WO 1998/034,665; WO 2000/078,381; U.S. Pat. No.6,581,594; US Patent Application; US 2009/0050156; US Patent Application2009/0044808.

Table of noise of prior masks (ISO 17510-2:2007, 10 cmH₂O pressure at 1m) A-weighted A-weighted sound power sound level dbA pressure dbA YearMask name Mask type (uncertainty) (uncertainty) (approx.) Glue-on (*)nasal 50.9 42.9 1981 ResCare standard (*) nasal 31.5 23.5 1993 ResMedMirage (*) nasal 29.5 21.5 1998 ResMed UltraMirage nasal 36 (3) 28 (3)2000 ResMed Mirage Activa nasal 32 (3) 24 (3) 2002 ResMed Mirage Micronasal 30 (3) 22 (3) 2008 ResMed Mirage SoftGel nasal 29 (3) 22 (3) 2008ResMed Mirage FX nasal 26 (3) 18 (3) 2010 ResMed Mirage Swift (*) nasalpillows 37 29 2004 ResMed Mirage Swift II nasal pillows 28 (3) 20 (3)2005 ResMed Mirage Swift LT nasal pillows 25 (3) 17 (3) 2008 ResMedSwift FX nasal pillows 25 (3) 17 (3) 2011 ResMed Mirage series I, II (*)full face 31.7 23.7 2000 ResMed UltraMirage full face 35 (3) 27 (3) 2004ResMed Mirage Quattro full face 26 (3) 18 (3) 2006 ResMed Mirage QuattroFX full face 27 (3) 19 (3) 2008 ((*) one specimen only, measured usingtest method specified in ISO3744 in CPAP mode at 10 cmH₂O)

Sound pressure values of a variety of objects are listed below

A-weighted sound pressure dbA Object (uncertainty) Notes Vacuum cleaner:Nilfisk 68 ISO3744 at 1 m Walter Broadly Litter Hog: B+ distance GradeConversational speech 60 1 m distance Average home 50 Quiet library 40Quiet bedroom at night 30 Background in TV studio 20

Nasal Pillow Technologies

One form of nasal pillow is found in the Adam Circuit manufactured byPuritan Bennett. Another nasal pillow, or nasal puff is the subject ofU.S. Pat. No. 4,782,832 (Trimble et al.), assigned to Puritan-BennettCorporation.

ResMed Limited has manufactured the following products that incorporatenasal pillows: SWIFT™ nasal pillows mask, SWIFT II™ nasal pillows mask,SWIFT LT™ nasal pillows mask, SWIFT FX™ nasal pillows mask and LIBERTYfull-face mask. The following patent applications, assigned to ResMedLimited, describe nasal pillows masks: International Patent ApplicationWO2004/073,778 (describing amongst other things aspects of ResMed SWIFT™nasal pillows), US Patent Application 2009/0044808 (describing amongstother things aspects of ResMed SWIFT LT nasal pillows); InternationalPatent Applications WO 2005/063,328 and WO 2006/130,903 (describingamongst other things aspects of ResMed LIBERTY™ full-face mask);International Patent Application WO 2009/052,560 (describing amongstother things aspects of ResMed SWIFT FX™ nasal pillows).

PAP Device

The air at positive pressure is typically supplied to the airway of apatient by a PAP device such as a motor-driven blower. The outlet of theblower is connected via a flexible delivery conduit to a patientinterface as described above.

Mandibular Repositioning

A mandibular repositioning device (MRD) is one of the treatment optionsfor sleep apnea. It is a custom made, adjustable oral applianceavailable from a dentist that holds the lower jaw in a forward positionduring sleep. This mechanical protrusion expands the space behind thetongue, puts tension on the pharyngeal walls to reduce collapse of theairway and diminishes palate vibration.

BRIEF SUMMARY OF THE TECHNOLOGY

The present technology is directed towards providing medical devicesused in the diagnosis, amelioration, treatment, or prevention ofrespiratory disorders having one or more of improved comfort, cost,efficacy, ease of use and manufacturability.

One aspect of the present technology relates to apparatus used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

Another aspect of the present technology relates to methods used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

One aspect of one form of the present technology is a patient interfacewith a seal-forming structure that is removable for cleaning. It is thedesire of the present technology to provide a patient interface that islight-weight compared to prior art patient interfaces, more unobtrusivecompared to prior art patient interfaces and more quiet in use comparedto prior art patient interfaces. It is also desirable to provide apatient interface that is intuitive to a patient when connecting maskcomponents prior to commencement of therapy and is also simple to adjustand wear for therapy.

An aspect of one form of the present technology is a patient interfacehaving a seal-forming structure that is locatable in position on thepatient interface via a hard-to-hard connection. Another aspect of oneform of the present technology is seal-forming structure of a patientinterface that is removable for cleaning without requiring disconnectionof a headgear portion of the patient interface.

An aspect of one form of the present technology is a patient interfacecomprising a seal-forming structure, a plenum chamber and a connectionportion, wherein the seal-forming structure and the plenum chamber areformed from a relatively soft material, and the connection portion isformed from relatively rigid material. In one form the connectionportion is removably connectable to a frame of the patient interface,e.g. via a snap-action, toggle or bi-stable mechanism. In one form theconnection portion is insert moulded to the plenum chamber.

An aspect of one form of the present technology is a patient interfacethat reduces or avoids contact with a septum and/or an upper lip of thepatient.

Another aspect of one form of the present technology is a patientinterface that is moulded or otherwise constructed with a clearlydefined perimeter shape which is intended to match that of an intendedwearer.

An aspect of one form of the present technology is a method ofmanufacturing the patient interface described herein. It is a desire ofthe present technology to provide a method of manufacture that has lesscomplexity than methods of manufacturing prior art patient interfaces toincrease manufacturing efficiency, uses less raw materials and requiresless assembly time by operators.

Another aspect of the present technology is directed to a patientinterface for delivery of a supply of pressurised air or breathable gasto an entrance of a patient's airways. The patient interface maycomprise: a cushion member that includes a retaining structure and aseal-forming structure permanently connected to the retaining structure;and a frame member, wherein the retaining structure and the frame memberare repeatedly removably attachable to one another; wherein a gaschamber is formed at least in part by engagement of the cushion memberand the frame member; and wherein an increase in air pressure within thecushion member causes a sealing force between the seal-forming structureand the frame member to increase.

In examples, (a) the seal-forming structure may be co-molded with theretaining structure, (b) the cushion member may be repeatedly removablyattachable to the frame member by pinching two opposing locations on thecushion member proximal to the retaining structure, (c) the seal-formingstructure may comprise a sealing lip that seals against the frame memberwhen the retaining structure and frame member are attached to oneanother, and when air pressure within the cushion member increases, thesealing lip is deflected towards the frame member to increase thesealing force, (d) the sealing lip may be a continuous inner peripheraledge integral to the seal-forming structure, (e) the retaining structureand the frame member may be more rigid than the seal-forming structure,(f) the retention structure may comprise a pair of barbs, (g) said framemember may comprise a channel configured to receive a respective matingfeature of said cushion member, (h) said cushion member may comprise achannel configured to receive a respective mating feature of said framemember, (i) said seal-forming structure may comprise a sealing flangeextending around a perimeter of said seal-forming structure to form aseal at the entrance of a patient's airway, (j) said frame member maycomprise a tongue portion constructed and arranged to effect a seal withsaid sealing flange, (k) the cushion member may comprise a plenumchamber having a posterior wall that is constructed and arranged to belocated adjacent an upper lip of a patient in use, and the plenumchamber may be located between the retaining structure and theseal-forming structure, (l) the patient interface may include apositioning and stabilising structure or a connector for a positioningand stabilising structure, (m) the patient interface may be directlyconnected to a gas delivery tube by a connection port (n), theconnection port may be formed in one piece with the frame of the patientinterface, (o) the connection port may be formed at an angle relative tothe frame, (p) the plenum chamber may include a concave, dipped, orsaddle-shaped region that spans the plenum chamber between the nasalpillows, and/or (q) the saddle-shaped region may span from a posteriorwall of the plenum chamber to an anterior wall of the plenum chamber.

Another aspect of the present technology is directed to a patientinterface to provide breathable gas to a patient. The patient interfacemay comprise: a plenum chamber having a plenum connection region; aseal-forming structure disposed on the plenum chamber; and a framecomprising a frame connection region and a headgear connection region;and a gas delivery tube, wherein the gas delivery tube is insert moldedto the frame.

Another aspect of the present technology is directed to a patientinterface to provide breathable gas to a patient. The patient interfacemay comprise: a plenum chamber having a plenum connection region; aseal-forming structure disposed on the plenum chamber; and a framecomprising a frame connection region and a headgear connection region;and a connection port to receive a gas delivery tube, wherein theconnection port is connected to the frame at a limited portion orportions of a periphery of the connection port.

Another aspect of the present technology is directed to a patientinterface to provide breathable gas to a patient. The patient interfacemay comprise: a plenum chamber having a plenum connection region; aseal-forming structure disposed on the plenum chamber; and a framecomprising a frame connection region and a headgear connection region;wherein the frame connection region is configured for attachment to theplenum chamber at the plenum connection region, and wherein a sealinglip is adapted to form a pneumatic seal between the plenum connectionregion and the frame connection region.

In examples, (a) the seal-forming structure may comprise a pair of nasalpillows constructed and arranged to provide a substantially sealed pathfor the breathable gas to the nares, and to form a seal at least in parton a columella region of a patient's nose, (b) each of the pair of nasalpillows may comprise a frustocone portion pneumatically connected to theplenum chamber by a stalk, (c) the frustocone portion may comprise asealing flange and a support flange, said sealing flange and saidsupport flange may be connected to the stalk by a flexible region, (d)the support flange may be adapted to press the sealing flange againstthe peripheral region of the nares of the patient, (e) the plenumchamber may comprise the sealing lip, said sealing lip located at theplenum connection region, (f) the sealing lip may be disposed annularlyabout the plenum chamber at the plenum connection region, (g) thesealing lip may be disposed about an interior periphery of the plenumchamber, (h) the sealing lip may be disposed about an exterior peripheryof the plenum chamber, (i) the sealing lip may depend from the plenumchamber at an angle and in a direction substantially opposite of theseal-forming structure, (j) the sealing lip may be constructed andarranged such that it is deformable in a direction substantially towardthe seal-forming structure such that a pneumatic seal is formed betweenthe plenum chamber and the frame when the frame is attached to theplenum chamber via the plenum connection region, (k) the sealing lip maybe disposed about the entire interior periphery of the plenum chamber,(l) the sealing lip may be disposed about the entire exterior peripheryof the plenum chamber, (m) the sealing lip and the plenum chamber maycomprise one piece, (n) the plenum connection region and the plenumchamber may be fixedly attached by co-molding or injection molding, (o)the plenum connection region and the plenum chamber may comprisedifferent materials, (p) the plenum chamber may comprise a softermaterial than the plenum connection region, (q) the plenum chamber maycomprise an elastomeric material and the plenum connection region maycomprise polycarbonate, high durometer silicone, or thermoplasticelastomer, (r) the material that comprises the plenum connection regionand the material that comprises the frame may be the same, (s) theplenum connection region may comprise at least one retention feature tofacilitate connection with the frame, and the frame may comprise atleast one complementary frame connection region to receive the at leastone retention feature corresponding thereto, (t) each of the at leastone retention features may comprise a barb, said barb may have a leadingsurface and a trailing surface and each of the least one frameconnection regions may comprise a lead-in surface and a retainingsurface, (u) the leading surface may be configured to contact thecorresponding lead-in surface of the at least one frame connectionregion during attachment of the plenum connection region to the framesuch that the at least one retention feature deforms in a directiongenerally opposite the lead-in surface, (u) complete engagement of theat least one retention feature to the at least one frame connectionregion may generate an audible click when the plenum connection regionis attached to the frame and the leading surface passes the lead-insurface, (v) said barb may depend from said at least one retentionfeature opposite an additional surface of the at least one retentionfeature, (w) the leading surface and the trailing surface of said barbmay be angled toward one another away from and with respect to theadditional surface, (x) the leading surface of said barb may be angledat about 60 degrees with respect to the additional surface, (y) thetrailing surface of said barb may be angled at about 75 degrees withrespect to the additional surface, (z) the trailing surface may beangled closer to perpendicular with respect to the additional surfacethan the leading surface such that a force required to attach the plenumconnection region to the frame is greater than a force required todetach the plenum connection region from the frame, (aa) the lead-insurface of the at least one frame connection region may be angled to beflush with the leading surface of the least one retention feature duringattachment, (bb) the retaining surface of the at least one frameconnection region may be angled to be flush with the trailing surface ofthe least one retention feature when the at least one frame connectionregion and the at least one retention feature are completely engaged,(cc) the at least one retention feature may comprise a first retentionfeature and a second retention feature and the at least one frameconnection region may comprise a first frame connection region and asecond frame connection region, (dd) the first retention feature may becomplementarily dimensioned with respect to the first frame connectionregion such that the second retention feature cannot be engaged to thefirst frame connection region, (ee) the frame may comprise a portadapted to connect to a conduit to supply supplemental oxygen, or tomeasure a pressure within the plenum chamber, (ff) the port may besubstantially cylindrical, (gg) the port and the frame may comprise onepiece, (hh) the port may extend from the frame in a directionsubstantially opposite the plenum chamber, (ii) the port may extendinferiorly from the frame, (jj) the frame may comprise at least onevent, (kk) the at least one vent may comprise mesh, (ll) the at leastone vent may comprise a pair of vents, each disposed on an anteriorsurface of the frame at opposite sides, (mm) the seal-forming structuremay serve both nares of the patient with a single orifice, (nn) thepatient interface may be directly connected to a gas delivery tube by aconnection port (oo), the connection port may be formed in one piecewith the frame of the patient interface, (pp) the connection port may beformed at an angle relative to the frame, (qq) the plenum chamber mayinclude a concave, dipped, or saddle-shaped region that spans the plenumchamber between the nasal pillows, and/or (rr) the saddle-shaped regionmay span from a posterior wall of the plenum chamber to an anterior wallof the plenum chamber.

Another aspect of one form of the present technology is a patientinterface that is moulded or otherwise constructed with a clearlydefined perimeter shape which is intended to match that of an intendedwearer.

One aspect of the present technology is directed to a positioning andstabilising structure for a patient interface device. The positioningand stabilising structure may comprise: at least one strap; and at leastone rigidiser arm, wherein the positioning and stabilising structure maybe arranged to position the at least one strap and the at least onerigidiser arm with regard to one another such that the at least onerigidiser arm imparts a desired shape to the at least one strap at arigidised portion of the at least one strap and allowing at least therigidised portion of the at least one strap to move relative to the atleast one rigidiser arm.

In examples, (a) the at least one rigidiser arm may be affixed to the atleast one strap in a limited area of the at least one strap, (b) thelimited area may be adjacent a pocket or a sleeve opening, (c) thepositioning and stabilising structure may comprise headgear for apatient interface device for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airway, (d) the at leastone rigidiser arm may be crescent shaped, (e) the at least one strap maybe made of an elastic textile material and the positioning andstabilising structure may be arranged such that the at least one strapis substantially free to move by elastically expanding and/orcontracting, relative to the at least one rigidiser arm, and along alongitudinal axis of the at least one strap and/or rigidiser arm, (f)the stretchable length of the at least one strap may remainsubstantially unaltered relative to the at least one strap without theat least one rigidiser arm, (g) the elastic textile material may be anyone from the group consisting of: elastane, TPE, nylon and silicone, (h)the positioning and stabilising structure may be able to stretch alongits substantial entire length, (i) the at least one strap may bestretchable and may be in the form of a sleeve arranged to slip over theat least one rigidiser arm, the arrangement being such that the at leastone strap maintains its substantially entire stretchable length and maybe able to substantially freely stretch over the at least one rigidiserarm, (j) the at least one strap may comprises hollow sleeve forreceiving the at least one rigidiser arm in place and at least oneopening, for receiving the at least one rigidiser arm into the sleeve,(k) the sleeve and the at least one rigidiser arm may be arranged toallow the at least one rigidiser arm to move substantially axiallyinside the sleeve, (j) an end portion of the at least one rigidiser armmay be affixed to the at least one strap, (k) the at least one rigidiserarm may be affixed to the at least one strap by sewing, welding, gluing,heat staking, clamping, buttoning, snapping a cover over the end, and/orsnapping on an external part, (j) if the at least one rigidiser arm isaffixed to the at least one strap by snapping on an external part,snapping on an external part may be achieved by aligning the at leastone strap and the at least one rigidiser arm, pushing the at least onerigidiser arm inside the sleeve, and fixing both sleeve and rigidiserarm to the external part, (k) the external part may be an external clipthat holds both the sleeve and a respective end of the at least onerigidiser arm, the clip may be adapted to attach an end of thepositioning and stabilising structure to a respective end of a maskframe, and the clip may be a part of the mask frame itself, (l) theimparted desired shape may direct the pressure of the positioning andstabilising structure to predetermined portions of a wearers' face, (m)a plurality of attachment points for attachment may be provided suchthat at least one fixation location is chosen and varied to allowadjustment of the at least one strap's elastic length, (n) the at leastone rigidiser arm may be incapable of stretching and may be relativelymore rigid than the at least one strap, (o) the at least one strap maycomprise elastic walls, said elastic walls being any one from the groupconsisting of: woven, knitted, braided, molded, and extruded, (p) thepositioning and stabilising structure may comprise two or more rigidiserarms symmetrically disposed on opposite sides of the patient's face, (q)the at least one rigidiser arm may be completely removable from the atleast one strap, (r) the positioning and stabilising structure maymaintain its entire operational length and is able to freely stretchalong the at least one rigidiser arm, (s) the at least one strap mayinclude two side strap portions arranged to extend from a patientinterface along the sides of a patient's head, and two back strapportions arranged to extend along the back of the patient's head, (t)the two back strap portions may not be adjustable except through theelasticity of the back strap portions or through increasing the backstrap portions in tightness equally by shortening the total length ofthe positioning and stabilising structure, (u) the positioning andstabilising structure may comprise three, four or more separate strapsconnected by two or more joints, (v) the at least one strap may comprisetwo pockets, each receiving a rigidiser arm to releasably secure the atleast one strap to the rigidiser arms, (w) the positioning andstabilising structure may comprise at least one retaining means, saidretaining means comprising a loop, a sleeve and/or a pocket, forreceiving the at least one rigidiser arm and holding the at least onerigidiser arm in place, (x) the at least one retaining means may beformed on or in the at least one strap, (y) the at least one rigidiserarm may be affixed to a guiding element provided to the at least onestrap, (z) the at least one rigidiser arm may be affixed to the at leastone strap at one localized point or area only, (aa) the guiding elementmay be a loop- or sheath-like portion or passage or a pocket into whichor through which the at least one rigidiser arm extends, (bb) theguiding element may allow longitudinal expansion or retraction of the atleast one strap relative to the at least one rigidiser arm and/or mayallow substantially free movement or floating of the at least onerigidiser arm relative to the at least one strap, (cc) the at least onestrap may comprises a back portion that is split into at least two backstraps, (dd) the at least two back straps may comprise a first backstrap adapted to engage the patient proximal to the crown of the headand a second back strap adapted to engage the patient proximal to therear of the head, (ee) each of the at least two back straps may beadapted to retain a patient interface against the nose of the patientwith substantially equal tension forces, (ff) when donned by thepatient, each of the at least two back straps may be in tension with asubstantially equal force, (gg) each of the at least two back straps maybe symmetrical and non-independently adjustable such that the at leasttwo back straps naturally center on respective sides of the crown of thehead of the, (hh) a split region may be defined between the at least twoback straps and the split region is about 200 mm in length, and/or (ii)a patient interface system, may comprise: a positioning and stabilisingstructure according to any one of the above examples; and a patientinterface comprising any one from the group consisting of: a nasalcannula, nasal prongs and a respiratory mask covering nose and/or mouthof a wearer, to a patient's face.

Another aspect of the present technology is directed to a patientinterface system to provide breathable gas to a patient. The patientinterface system may comprise: a patient interface including aseal-forming structure to provide a pneumatic connection to the airwaysof the patient; and a positioning and stabilising structure including atleast one strap and at least one rigidiser arm and configured toreleasably retain the patient interface on the patient, wherein a shapedportion of the at least one strap is adapted to take on a shape of theat least one rigidiser arm, said shaped portion being arranged to movealong the longitudinal axis of the at least one rigidiser arm.

In examples, (a) the at least one rigidiser arm may be affixed to the atleast one strap in a limited area of the at least one strap, (b) thelimited area may be adjacent a pocket or a sleeve opening, (c) thepositioning and stabilising structure may comprises headgear, (d) the atleast one rigidiser arm may be crescent shaped, (e) the at least onestrap may be made of an elastic textile material and the positioning andstabilising structure may be arranged such that the at least one strapis substantially free to move by elastically expanding and/orcontracting, relative to the at least one rigidiser arm, and along alongitudinal axis of the at least one strap and/or rigidiser arm, (f)the stretchable length of the at least one strap may remainsubstantially unaltered relative to the at least one strap without theat least one rigidiser arm, (g) the elastic textile material may be anyone from the group consisting of: elastane, TPE, nylon and silicone, (h)the positioning and stabilising structure may be able to stretch alongits substantial entire length, (i) the at least one strap may bestretchable and may be in the form of a sleeve arranged to slip over theat least one rigidiser arm, the arrangement being such that the at leastone strap maintains its substantially entire stretchable length and isable to substantially freely stretch over the at least one rigidiserarm, (j) the at least one strap may comprise a hollow sleeve forreceiving the at least one rigidiser arm in place and at least oneopening, for receiving the at least one rigidiser arm into the sleeve,(k) the sleeve and the at least one rigidiser arm may be arranged toallow the at least one rigidiser arm to move substantially axiallyinside the sleeve, (l) an end portion of the at least one rigidiser armmay be affixed to the at least one strap, (m) the at least one rigidiserarm may be affixed to the at least one strap by sewing, welding, gluing,heat staking, clamping, buttoning, snapping a cover over the end, and/orsnapping on an external part, (n) if the at least one rigidiser arm isaffixed to the at least one strap by snapping on an external part,snapping on an external part may be achieved by aligning the at leastone strap and the at least one rigidiser arm, pushing the at least onerigidiser arm inside the sleeve, and fixing both sleeve and rigidiserarm to the external part, (o) the external part may be an external clipthat holds both the sleeve and a respective end of the at least onerigidiser arm, the clip may be adapted to attach an end of thepositioning and stabilising structure to a respective end of a maskframe, and the clip may be a part of the mask frame itself, (p) theshaped portion may direct the pressure of the positioning andstabilising structure to predetermined portions of a wearers' face, (q)a plurality of attachment points for attachment may be provided suchthat at least one fixation location may be chosen and varied to allowadjustment of the at least one strap's elastic length, (r) the at leastone rigidiser arm may be incapable of stretching and is relatively morerigid than the at least one strap, (s) the at least one strap maycomprise elastic walls, said elastic walls being any one from the groupconsisting of: woven, knitted, braided, molded, and extruded, (t) thepatient interface system may comprise two or more rigidiser armssymmetrically disposed on opposite sides of the patient's face, (u) theat least one rigidiser arm may be completely removable from the at leastone strap, (v) the positioning and stabilising structure may maintainsits entire operational length and may be able to freely stretch alongthe at least one rigidiser arm, (w) the at least one strap may includetwo side strap portions arranged to extend from a patient interfacealong the sides of a patient's head, and two back strap portionsarranged to extend along the back of the patient's head, (x) the twoback strap portions may not be adjustable except through the elasticityof the back strap portions or through increasing the back strap portionsin tightness equally by shortening the total length of the positioningand stabilising structure, (y) the patient interface system may comprisethree, four or more separate straps connected by two or more joints, (z)the at least one strap may comprise two pockets, each receiving arigidiser arm to releasably secure the at least one strap to therigidiser arms, (aa) the positioning and stabilising structure maycomprise at least one retaining means, said retaining means comprising aloop, a sleeve and/or a pocket, for receiving the at least one rigidiserarm and holding the at least one rigidiser arm in place, (bb) the atleast one retaining means may be formed on or in the at least one strap,(cc) the at least one rigidiser arm may be affixed to a guiding elementprovided to the at least one strap, (dd) the at least one rigidiser armmay be affixed to the at least one strap at one localized point or areaonly, (ee) the guiding element may be a loop- or sheath-like portion orpassage or a pocket into which or through which the at least onerigidiser arm extends, (ff) the guiding element may allow longitudinalexpansion or retraction of the at least one strap relative to the atleast one rigidiser arm and/or may allow substantially free movement orfloating of the at least one rigidiser arm relative to the at least onestrap, (gg) the at least one strap may comprise a back portion that issplit into at least two back straps, (hh) the at least two back strapsmay comprise a first back strap adapted to engage the patient proximalto the crown of the head and a second back strap adapted to engage thepatient proximal to the rear of the head, (ii) each of the at least twoback straps may be adapted to retain a patient interface against thenose of the patient with substantially equal tension forces, (jj) whendonned by the patient, each of the at least two back straps may be intension with a substantially equal force, (kk) each of the at least twoback straps may be symmetrical and non-independently adjustable suchthat the at least two back straps naturally center on respective sidesof the crown of the head of the patient, (ll) the patient interfacesystem may include a split region is defined between the at least twoback straps and the split region is about 200 mm in length, and/or (mm)the patient interface may comprise any one from the group consisting of:a nasal cannula, nasal prongs and a respiratory mask covering noseand/or mouth of a wearer, to a patient's face.

Another aspect of the present technology is directed to a positioningand stabilising structure, comprising: at least one strap; and at leastone rigidiser arm, wherein the positioning and stabilising structure isarranged to position the at least one strap and the at least onerigidiser arm with regard to one another such that the at least onerigidiser arm imparts a desired shape to the at least one strap at arigidised portion, and wherein the at least one rigidiser arm is adaptedto connect to a patient interface by a flexible joint such that thepatient interface may be displaced to engage with the nose of thepatient.

In examples, (a) the at least one rigidiser arm may be affixed to the atleast one strap in a limited area of the at least one strap, (b) thelimited area may be adjacent a pocket or a sleeve opening, (c) thepositioning and stabilising structure may comprise headgear for apatient interface device for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airway, (d) the at leastone rigidiser arm may be crescent shaped, (e) the at least one strap maybe made of an elastic textile material and the positioning andstabilising structure may be arranged such that the at least one strapis substantially free to move by elastically expanding and/orcontracting, relative to the at least one rigidiser arm, and along alongitudinal axis of the at least one strap and/or rigidiser arm, (f)the stretchable length of the at least one strap may remainsubstantially unaltered relative to the at least one strap without theat least one rigidiser arm, (g) the elastic textile material may be anyone from the group consisting of: elastane, TPE, nylon and silicone, (h)the positioning and stabilising structure may be able to stretch alongits substantial entire length, (i) the at least one strap may bestretchable and is in the form of a sleeve arranged to slip over the atleast one rigidiser arm, the arrangement being such that the at leastone strap maintains its substantially entire stretchable length and isable to substantially freely stretch over the at least one rigidiserarm, (j) the at least one strap may comprise a hollow sleeve forreceiving the at least one rigidiser arm in place and at least oneopening, for receiving the at least one rigidiser arm into the sleeve,(k) the sleeve and the at least one rigidiser arm may be arranged toallow the at least one rigidiser arm to move substantially axiallyinside the sleeve, (l) an end portion of the at least one rigidiser armmay be affixed to the at least one strap, (m) the at least one rigidiserarm may be affixed to the at least one strap by sewing, welding, gluing,heat staking, clamping, buttoning, snapping a cover over the end, and/orsnapping on an external part, (n) if the at least one rigidiser arm isaffixed to the at least one strap by snapping on an external part,snapping on an external part may be achieved by aligning the at leastone strap and the at least one rigidiser arm, pushing the at least onerigidiser arm inside the sleeve, and fixing both sleeve and rigidiserarm to the external part, (o) the external part may be an external clipthat holds both the sleeve and a respective end of the at least onerigidiser arm, the clip may be adapted to attach an end of thepositioning and stabilising structure to a respective end of a maskframe, and the clip may be a part of the mask frame itself, (p) theimparted desired shape may direct the pressure of the positioning andstabilising structure to predetermined portions of a wearers' face, (q)a plurality of attachment points for attachment may be provided suchthat at least one fixation location may be chosen and varied to allowadjustment of the at least one strap's elastic length, (r) the at leastone rigidiser arm may be incapable of stretching and may be relativelymore rigid than the at least one strap, (s) the at least one strap maycomprise elastic walls, said elastic walls being any one from the groupconsisting of: woven, knitted, braided, molded, and extruded, (t) thepositioning and stabilising structure may comprise two or more rigidiserarms symmetrically disposed on opposite sides of the patient's face, (u)the at least one rigidiser arm may be completely removable from the atleast one strap, (v) the positioning and stabilising structure maymaintain its entire operational length and is able to freely stretchalong the at least one rigidiser arm, (w) the at least one strap mayinclude two side strap portions arranged to extend from a patientinterface along the sides of a patient's head, and two back strapportions arranged to extend along the back of the patient's head, (x)the two back strap portions may not be adjustable except through theelasticity of the back strap portions or through increasing the backstrap portions in tightness equally by shortening the total length ofthe positioning and stabilising structure, (y) the positioning andstabilising structure may comprise three, four or more separate strapsconnected by two or more joints, (z) the at least one strap may comprisetwo pockets, each receiving a rigidiser arm to releasably secure the atleast one strap to the rigidiser arms, (aa) the positioning andstabilising structure may comprise at least one retaining means, saidretaining means comprising a loop, a sleeve and/or a pocket, forreceiving the at least one rigidiser arm and holding the at least onerigidiser arm in place, (bb) the at least one retaining means may beformed on or in the at least one strap, (cc) the at least one rigidiserarm may be affixed to a guiding element provided to the at least onestrap, (dd) the at least one rigidiser arm may be affixed to the atleast one strap at one localized point or area only, (ee) the guidingelement may be a loop- or sheath-like portion or passage or a pocketinto which or through which the at least one rigidiser arm extends, (ff)the guiding element may allow longitudinal expansion or retraction ofthe at least one strap relative to the at least one rigidiser arm and/ormay allow substantially free movement or floating of the at least onerigidiser arm relative to the at least one strap, (gg) the at least onestrap may comprise a back portion that is split into at least two backstraps, (hh) the at least two back straps may comprise a first backstrap adapted to engage the patient proximal to the crown of the headand a second back strap adapted to engage the patient proximal to therear of the head, (ii) each of the at least two back straps may beadapted to retain a patient interface against the nose of the patientwith substantially equal tension forces, (jj) when donned by thepatient, each of the at least two back straps may be in tension with asubstantially equal force, (kk) each of the at least two back straps maybe symmetrical and non-independently adjustable such that the at leasttwo back straps naturally center on respective sides of the crown of thehead of the patient, (ll) a split region may be defined between the atleast two back straps and the split region is about 200 mm in length,and/or (mm) a patient interface system may comprise: a positioning andstabilising structure according to any one of the above examples; and apatient interface comprising any one from the group consisting of: anasal cannula, nasal prongs and a respiratory mask covering nose and/ormouth of a wearer, to a patient's face.

Another aspect of the present technology is directed to a positioningand stabilising structure. The positioning and stabilising structure maycomprise: at least one strap including at least two back straps, whereineach of the at least two back straps are symmetrical andnon-independently adjustable such that the at least two back strapsnaturally center on respective sides of the crown of the head of thepatient.

In examples, (a) the positioning and stabilising structure may compriseat least one rigidiser arm, (b) the at least one rigidiser arm may beaffixed to the at least one strap in a limited area of the at least onestrap, (c) the limited area may be adjacent a pocket or a sleeveopening, (d) the positioning and stabilising structure may compriseheadgear for a patient interface device for delivery of a supply ofpressurised air or breathable gas to an entrance of a patient's airway,(e) the at least one rigidiser arm may be crescent shaped, (f) the atleast one strap may be made of an elastic textile material and thepositioning and stabilising structure may be arranged such that the atleast one strap is substantially free to move by elastically expandingand/or contracting, relative to the at least one rigidiser arm, andalong a longitudinal axis of the at least one strap and/or rigidiserarm, (g) the stretchable length of the at least one strap may remainsubstantially unaltered relative to the at least one strap without theat least one rigidiser arm, (h) the elastic textile material may be anyone from the group consisting of: elastane, TPE, nylon and silicone, thepositioning and stabilising structure may be able to stretch along itssubstantial entire length, (i) the at least one strap may be stretchableand may be in the form of a sleeve arranged to slip over the at leastone rigidiser arm, the arrangement being such that the at least onestrap maintains its substantially entire stretchable length and is ableto substantially freely stretch over the at least one rigidiser arm, (j)the at least one strap may comprise a hollow sleeve for receiving the atleast one rigidiser arm in place and at least one opening, for receivingthe at least one rigidiser arm into the sleeve, (k) the sleeve and theat least one rigidiser arm may be arranged to allow the at least onerigidiser arm to move substantially axially inside the sleeve, (l) anend portion of the at least one rigidiser arm may be affixed to the atleast one strap, (m) the at least one rigidiser arm may be affixed tothe at least one strap by sewing, welding, gluing, heat staking,clamping, buttoning, snapping a cover over the end, and/or snapping onan external part, (n) if the at least one rigidiser arm is affixed tothe at least one strap by snapping on an external part, snapping on anexternal part may be achieved by aligning the at least one strap and theat least one rigidiser arm, pushing the at least one rigidiser arminside the sleeve, and fixing both sleeve and rigidiser arm to theexternal part, (o) the external part may be an external clip that holdsboth the sleeve and a respective end of the at least one rigidiser arm,the clip may be adapted to attach an end of the positioning andstabilising structure to a respective end of a mask frame, and the clipmay be a part of the mask frame itself, (p) a plurality of attachmentpoints for attachment may be provided such that at least one fixationlocation may be chosen and varied to allow adjustment of the at leastone strap's elastic length, (q) the at least one rigidiser arm may beincapable of stretching and is relatively more rigid than the at leastone strap, (r) the at least one strap comprises elastic walls, saidelastic walls being any one from the group consisting of: woven,knitted, braided, molded, and extruded, comprising two or more rigidiserarms symmetrically disposed on opposite sides of the patient's face, (s)the at least one rigidiser arm may be completely removable from the atleast one strap, (t) the positioning and stabilising structure maymaintains its entire operational length and is able to freely stretchalong the at least one rigidiser arm, (u) the at least one strap mayinclude two side strap portions arranged to extend from a patientinterface along the sides of a patient's head, and two back strapportions arranged to extend along the back of the patient's head, (v)the two back strap portions may not be adjustable except through theelasticity of the back strap portions or through increasing the backstrap portions in tightness equally by shortening the total length ofthe positioning and stabilising structure, (w) the positioning andstabilising structure may comprise three, four or more separate strapsconnected by two or more joints, (x) the at least one strap may comprisetwo pockets, each receiving a rigidiser arm to releasably secure the atleast one strap to the rigidiser arms, (y) the positioning andstabilising structure may comprise at least one retaining means, saidretaining means comprising a loop, a sleeve and/or a pocket, forreceiving the at least one rigidiser arm and holding the at least onerigidiser arm in place, (z) the at least one retaining means is formedon or in the at least one strap, (aa) the at least one rigidiser arm maybe affixed to a guiding element provided to the at least one strap, (bb)the at least one rigidiser arm may be affixed to the at least one strapat one localized point or area only, (cc) the guiding element may be aloop- or sheath-like portion or passage or a pocket into which orthrough which the at least one rigidiser arm extends, (dd) the guidingelement may allow longitudinal expansion or retraction of the at leastone strap relative to the at least one rigidiser arm and/or may allowsubstantially free movement or floating of the at least one rigidiserarm relative to the at least one strap, (ee) the at least two backstraps may comprise a first back strap adapted to engage the patientproximal to the crown of the head and a second back strap adapted toengage the patient proximal to the rear of the head, (ff) each of the atleast two back straps may be adapted to retain a patient interfaceagainst the nose of the patient with substantially equal tension forces,(gg) when donned by the patient, each of the at least two back strapsmay be in tension with a substantially equal force, (hh) a split regionmay be defined between the at least two back straps and the split regionis about 200 mm in length, and/or (ii) a patient interface system maycomprise: a positioning and stabilising structure according to any oneof the examples above; and a patient interface comprising any one fromthe group consisting of: a nasal cannula, nasal prongs and a respiratorymask covering nose and/or mouth of a wearer, to a patient's face.

Another aspect of the present technology is directed to a positioningand stabilising structure. The positioning and stabilising structure maycomprise: at least one strap including a pair of side straps and a pairof back straps positioned between each of the pair of side straps, andwherein the pair of side straps and the pair of back straps are unitary.

In examples, (a) the positioning and stabilising structure may comprisea split region defined between the pair of back straps, (b) the splitregion initiates at a distal end of each of the pair of back straps, (c)each distal end may comprise a reinforced portion adjacent to the splitregion, (d) the at least one strap may be more stretchable along itslongitudinal axis than its lateral axis, (e) the at least one strap mayinclude a hole at a proximal end of each of the pair of side straps, thehole being shaped and dimensioned to receive the insertion of arigidiser arm, (f) the at least one strap may comprise a warp-knitted orwoven material and/or (g) the at least one strap may be tubular.

Another aspect of the present technology is directed to a method fordonning a patient interface by a patient, the patient interfaceincluding a positioning and stabilising structure. The method maycomprise: stretching the positioning and stabilising structure away fromthe patient interface; placing a seal-forming structure of the patientinterface against airways of the patient; releasing a portion of tensionof the positioning and stabilising structure by locating a rear portionof the positioning and stabilising structure against a rear portion ofthe patient's head; and adjusting tension of the positioning andstabilising structure by pulling apart back straps of the rear portionof the positioning and stabilising structure.

Another aspect of the present technology is directed to a patientinterface system. The patient interface system may comprise: at leastone strap including at least two back straps having a split regiontherebetween; a patient interface including a seal-forming structure andconnectable to the at least one strap; wherein the at least two backstraps are adjustably separable such that when the seal-formingstructure is placed against the airways of the patient a tension sealingforce generated against the patient interface by the at least one strapis greatest when an angle between the at least two back straps is zero.

In examples, (a) the tension sealing force may decrease as the anglebetween the at least two back straps increases, (b) a starting anglebetween the at least two back straps may be zero to allow a patient toadjust the tension sealing force by increasing the angle between the atleast two back straps, (c) the angle between the at least two backstraps may be less than or equal to 180°, and/or (d) when the anglebetween the at least two back straps is about 180° the tension sealingforce may be about 40% less than the tension sealing force when theangle between the at least two back straps is about zero.

Another aspect of the present technology is directed to a method forrepeatedly engaging a positioning and stabilising structure to a patientinterface device. The method may comprise: inserting an inextensiblerigidiser arm via an opening of a hollow stretchable fabric strap into aportion of the strap; and releasably securing an end portion of thestrap to the rigidiser arm; wherein the positioning and stabilisingstructure is arranged to position the strap and the rigidiser arm withregard to one another such that the rigidiser arm imparts a desiredshape to the strap at a rigidised portion while allowing the rigidisedportion of the strap to freely move relative to the rigidiser arm.

In examples, (a) the rigidiser arm may be permanently connected to amask frame of the patient interface device, (b) the end portion of thestrap may be a pocketed end that is secured to a respective catchingmember of the rigidiser arm, and/or (c) the pocketed end is wrapped overthe respective catching member of the rigidiser arm.

In another aspect, there is provided a method for manufacturing apatient interface for the treatment of respiratory disorders. The methodcomprises: cutting a vent portion from a textile formed by interlacingfibers. The textile has a predetermined amount of porosity.

The method comprises holding the vent portion in a mold.

The method comprises permanently connecting the held vent portion to amask frame made from a plastic material to form a vent of the patientinterface to washout exhaled air (including exhaled carbon dioxide).

Alternatively, the method comprises overmolding the held vent portion toa mask frame with a mechanical interlock between the vent portion andmask frame to form a vent of the patient interface to washout exhaledair (including exhaled carbon dioxide). The mechanical interlockprovides a permanent connection between the vent portion and the maskframe such that the vent cannot be removed from the mask frame. Apossible mechanical interlock is provided by one or more mushroom-shapedmechanical interlock elements. A pre-treatment can be applied on theintended bonding surface of the vent portion and the mask frameresulting in micro-roughness to improve bond strength.

The method may further comprise permanently connecting a first ventportion having a first airflow rate to the mask frame. The method mayalso comprise permanently connecting a second vent portion having asecond airflow rate that is different to the first airflow rate to themask frame. The first and second vent portions are selected if theaverage combined first and second airflow rates is within apredetermined range.

The interlacing fibers may be made from a thermoplastic polymer. Thethermoplastic polymer may be any one from the group consisting of:polypropylene, polycarbonate, nylon and polyethylene. The thermoplasticpolymer may be SEFAR material Tetex Mono 05-1010-K 080 wovenpolypropylene material.

The permanent connection may be obtained by molecular adhesion using anyone from the group consisting of: overmolding, co-injection molding andtwo shot (2K) injection molding.

The patient interface of the method may be any one from the groupconsisting of: nasal mask, full-face mask and nasal pillows. Preferably,the patient interface is nasal pillows or nasal cradle.

The cutting may be any one from the group consisting of: laser cutting,ultrasonic cutting and mechanical cutting.

The vent may be substantially in the shape of a semi-circle or D-shaped.

The textile may be provided in the form of a roll or ribbon beforecutting the vent portion.

The vent may have a maximum width of about 16 mm to about 21 mm,preferably, about 18.2 mm to 18.6 mm, and a maximum height of about 19mm to about 24 mm, preferably, 21.6 mm to 22 mm, and a thickness ofabout 0.36 mm to about 0.495 mm, preferably, 0.40 to 0.45 mm.

The mask frame may have two vents. A first vent is positioned on theleft side of the mask frame. A second vent is positioned on the rightside of the mask frame. The first and second vents are separated by anaperture for receiving an air delivery tube.

The method may further comprise selectively reducing the amount ofporosity of the vent portion if the airflow rate through the ventportion exceeds a predetermined range.

The predetermined range may be about 42 to about 59 liters per minute at20 cm H₂O pressure, preferably, about 47 to about 53 liters per minuteat 20 cm H₂O pressure.

The airflow rate through the SEFAR material Tetex Mono 05-1010-K 080woven polypropylene material may be about 37 to about 64 liters at 20 cmH₂O pressure, preferably, about 42 to about 58 liters at 20 cm H₂Opressure.

The porosity of the vent portion may be reduced by any one from thegroup consisting of: heat staking, plastic deformation by compression,ultrasonic welding, applying a sealant and applying a thin film. Thesealant may be a hot melt adhesive.

The porosity of the vent portion may be reduced by partially occludingor by fully occluding holes in the vent portion.

The porosity of a continuous peripheral edge region of the vent portionmay be reduced.

In a second aspect, there is provided a method for manufacturing a ventfor washout of exhaled air (including exhaled carbon dioxide) from apatient interface.

The method comprises cutting a vent portion from a semi-permeablematerial having a predetermined amount of porosity to diffuse airflow.

The method also comprises permanently connecting the vent portion to amask frame of a patient interface to form the vent. The predeterminedamount of porosity is such that an airflow rate of approximately 42 to59 liters per minute at 20 cm H₂O pressure of respiratory gas from thepatient interface is obtained and an A-weighted sound power level lessthan or equal to 25 dbA, with uncertainty 3 dbA and an A-weighted soundpressure at a distance of 1 meter greater than or equal to 17 dbA withuncertainty 3 dbA are generated. Preferably the A-weighted sound powerlevel is about 22 dbA and the A-weighted sound pressure is about 13 dbA.

The airflow rate may be 47 to 53 liters per minute at 20 cm H₂O pressureof respiratory gas.

In another aspect, there is provided a patient interface for thetreatment of respiratory disorder. The patient interface comprises avent to washout exhaled air (including exhaled carbon dioxide). The ventis connected to a vent cap made from a plastic material. The vent cap isremovably engageable with a mask frame at a vent orifice defined in themask frame. The vent is made from a textile formed by interlacingfibers. The textile has a predetermined amount of porosity.

The vent may have a portion occluded by heat staking to obtain thepredetermined amount of porosity.

The vent may have a superficial area of about 201.6 mm² to about 278.6mm².

The superficial area of the vent may have a total open area ofapproximately 1% to 10%.

Another aspect of the present technology may be directed to a gasdelivery tube to supply breathable gas from a respiratory apparatus. Thegas delivery tube may comprise a helical coil comprised of a pluralityof adjacent coils, each coil separated by a width and having an outersurface defining a coil diameter; and a web of material coaxial to thehelical coil attached to the helical coil between adjacent ones of theplurality of adjacent coils and having at least one fold extendingradially outward between adjacent ones of the plurality of adjacentcoils, said at least one fold defined by a predetermined fold line,wherein a vertex of said at least one fold defines a fold diameter,wherein when the gas delivery tube is in a neutral state the coildiameter being substantially equal to the fold diameter.

In examples, (a) the web of material may comprise the at least one foldextending radially outward along at least one lengthwise portion of thegas delivery tube, (b) a slope angle of the web of material may increasefrom the helical coil to the vertex of the at least one fold when thegas delivery tube is in a neutral state, (c) the web of material mayhave an asymmetrical cross-sectional profile about the predeterminedfold line, (d) the predetermined fold line may be spaced evenly betweenadjacent ones of the plurality of adjacent coils, (e) the widthseparating adjacent ones of the plurality of adjacent coils may be equalto a width of the helical coil when the gas delivery tube is in aneutral state, (f) the helical coil may comprise a greater proportion ofa superficial surface area of the gas delivery tube than the at leastone fold of the web of material, (g) an outer portion of the helicalcoil may have a rounded profile, (h) an outer surface of the helicalcoil may have a radius of curvature of 44 mm under its own weight whendraped over a cylinder having a 13 mm diameter, (i) an outer portion ofthe helical coil may have an oval-shaped profile, (j) the helical coilmay have a greater thickness than the web of material, (k) the web ofmaterial may have a substantially uniform thickness, (l) the helicalcoil may comprise a thermoplastic elastomer, (m) the web of material maycomprise a thermoplastic elastomer, (n) the web of material and thehelical coil may be bonded to form a uniform and continuous innersurface of the gas delivery tube, (o) the at least one fold may extendradially outward between alternating ones of the plurality of adjacentcoils, (p) the helical coil may have a pitch of about 3.2 mm to about4.7 mm, (q) the helical coil may have a pitch of about 4.5 mm to about4.7 mm, (r) the helical coil may have a spring stiffness of about 0.03N/mm, (s) an internal diameter of the tube may be about 18 mm when in aneutral state, and/or (t) the gas delivery tube may comprise one ofthree different states: a neutral state wherein the gas delivery tubecomprises a neutral length, an extended state wherein the gas deliverytube is extended to an extended length that is greater than the neutrallength, and a compressed state wherein the gas delivery tube iscompressed to a compressed length that is less than the neutral length.

Another aspect of the present technology is directed to a respiratorytherapy system to supply breathable gas to a patient. The respiratorytherapy system may comprise: a respiratory mask assembly to be worn bythe user during therapy; a gas delivery tube according to at least oneof the examples described in the previous paragraph, said gas deliverytube fixedly attached at a first end to the respiratory mask assemblyand having a rotatable adapter fixedly attached to a second end; anadditional gas delivery tube being different from the gas delivery tuberotatably attached at a third end to the gas delivery tube by therotatable adapter; and/or a respiratory apparatus to generate a flow ofbreathable gas connected to said additional gas delivery tube at afourth end.

Another aspect of the present technology is directed to a gas deliverytube to supply breathable gas from a respiratory apparatus. The gasdelivery tube may comprise a helical coil comprised of a plurality ofadjacent coils, each coil separated by a width; and a web of materialcoaxial to the helical coil attached to the helical coil betweenadjacent ones of the plurality of adjacent coils, wherein the widthseparating adjacent ones of the plurality of adjacent coils issubstantially equal to a width of the helical coil when the gas deliverytube is in a neutral state.

In examples, (a) the web of material may comprise at least one foldextending radially outward between adjacent ones of the plurality ofadjacent coils, said fold defined by a predetermined fold line andhaving a vertex, (b) the web of material may comprise the at least onefold extending radially outward along at least one lengthwise portion ofthe gas delivery tube, (c) the at least one fold may be spaced evenlybetween adjacent ones of the plurality of adjacent coils, (d) thehelical coil may comprise a greater proportion of a superficial surfacearea of the gas delivery tube than the at least one fold of the web ofmaterial, (e) an outer surface of the helical coil may define a coildiameter, a vertex of said at least one fold may define a fold diameter,and when the gas delivery tube is in a neutral state the coil diametermay be substantially equal to the fold diameter, (f) a slope angle ofthe web of material may increase from the helical coil to the vertex ofthe at least one fold when the gas delivery tube is in the neutralstate, (g) the web of material may have an asymmetrical cross-sectionalprofile about the predetermined fold line, (h) an outer portion of thehelical coil may have a rounded profile, (i) an outer portion of thehelical coil may have a radius of curvature of 44 mm under its ownweight when draped over a cylinder having a 13 mm diameter, (j) an outerportion of the helical coil may have an oval-shaped profile, (k) thehelical coil may have a greater thickness than the web of material, (l)the web of material may have a substantially uniform thickness, (m) thehelical coil may comprise a thermoplastic elastomer, (n) the web ofmaterial may comprise a thermoplastic elastomer, (o) the web of materialand the helical coil may be bonded to form a uniform and continuousinner surface of the gas delivery tube, (p) the web of material maycomprise at least one fold extending radially outward betweenalternating ones of the plurality of adjacent coils, (q) the helicalcoil may have a pitch of about 3.2 mm to about 4.7 mm, (r) the helicalcoil may have a pitch of about 4.5 mm to about 4.7 mm, (s) the helicalcoil may have a spring stiffness of about 0.03 N/mm, (t) an internaldiameter of the tube may be about 18 mm when in a neutral state, and/or(u) the gas delivery tube may comprise one of three different states: aneutral state wherein the gas delivery tube comprises a neutral length,an extended state wherein the gas delivery tube is extended to anextended length that is greater than the neutral length, and acompressed state wherein the gas delivery tube is compressed to acompressed length that is less than the neutral length.

Another aspect of the present technology is directed to a respiratorytherapy system to supply breathable gas to a patient. The respiratorytherapy system may comprise: a respiratory mask assembly to be worn bythe user during therapy; a gas delivery tube according to at least oneof the examples described in the previous paragraph, said gas deliverytube fixedly attached at a first end to the respiratory mask assemblyand having a rotatable adapter fixedly attached to a second end; anadditional gas delivery tube being different from the gas delivery tuberotatably attached at a third end to the gas delivery tube by therotatable adapter; and/or a respiratory apparatus to generate a flow ofbreathable gas connected to said additional gas delivery tube at afourth end.

Another aspect of the present technology may be directed to a gasdelivery tube to supply breathable gas from a respiratory apparatus. Thegas delivery tube may comprise a helical coil comprised of a pluralityof adjacent coils, each coil separated by a width; and a web of materialcoaxial to the helical coil attached to the helical coil betweenadjacent ones of the plurality of adjacent coils and having at least onefold extending radially outward between adjacent ones of the pluralityof adjacent coils, said at least one fold defined by a predeterminedfold line, wherein a vertex of said at least one fold defines a folddiameter, wherein a slope angle of the web of material increases fromthe helical coil to the vertex of the at least one fold when the gasdelivery tube is in a neutral state.

In examples, (a) the at least one fold may extend radially outward alongat least one lengthwise portion of the gas delivery tube, (b) the atleast one fold may be spaced evenly between adjacent ones of theplurality of adjacent coils, (c) an outer surface of the helical coilmay define a coil diameter, a vertex of said at least one fold maydefine a fold diameter, and when the gas delivery tube is in a neutralstate the coil diameter may be substantially equal to the fold diameter,(d) the helical coil may comprise a greater proportion of a superficialsurface area of the gas delivery tube than the vertex of the at leastone fold, (e) an outer portion of the helical coil may have a roundedprofile, (f) an outer portion of the helical coil may have a radius ofcurvature of 44 mm under its own weight when draped over a cylinderhaving a 13 mm diameter, (g) an outer portion of the helical coil mayhave an oval-shaped profile, (h) the helical coil may have a greaterthickness than the web of material, (i) the web of material may have asubstantially uniform thickness, (j) the helical coil may comprise athermoplastic elastomer, (k) the web of material may comprise athermoplastic elastomer, (l) the web of material and the helical coilmay be bonded to form a uniform and continuous inner surface of the gasdelivery tube, (m) the web of material may comprise at least one foldextending radially outward between alternating ones of the plurality ofadjacent coils, (n) the helical coil may have a pitch of about 3.2 mm toabout 4.7 mm, (o) the helical coil may have a pitch of about 4.5 mm toabout 4.7 mm, (p) the helical coil may have a spring stiffness of about0.03 N/mm, (q) an internal diameter of the tube may be about 18 mm whenin a neutral state, and/or (r) the gas delivery tube may comprise one ofthree different states: a neutral state wherein the gas delivery tubecomprises a neutral length, an extended state wherein the gas deliverytube is extended to an extended length that is greater than the neutrallength, and a compressed state wherein the gas delivery tube iscompressed to a compressed length that less than the neutral length.

Another aspect of the present technology is directed to a gas deliverytube to supply breathable gas from a respiratory apparatus. The gasdelivery tube may comprise: a plurality of coils each separated by awidth; and a web of material coaxial to the coils attached to the coilsbetween adjacent ones of the plurality of coils and having at least onefold extending radially outward between adjacent ones of the pluralityof coils, said at least one fold defined by a peak, wherein said web ofmaterial comprises a humped portion adjacent to a first side of thecoils and a slanted portion adjacent to a second side of the coils, saidsecond side opposite said first side, and wherein when the gas deliverytube is in a neutral state a slope of the web of material is steeperfrom the slanted portion to the adjacent peak than a slope of the web ofmaterial from the humped portion to the adjacent peak.

In examples, (a) the at least one fold may extend radially outward alongat least one lengthwise portion of the gas delivery tube, (b) the atleast one fold may be spaced evenly between adjacent ones of theplurality of coils, (c) an outer surface of the coils may define a coildiameter, the peak of said at least one fold may define a fold diameter,and when the gas delivery tube is in a neutral state the coil diametermay be substantially equal to the fold diameter, (d) the coils maycomprise a greater proportion of a superficial surface area of the gasdelivery tube than the peak of the at least one fold, (e) an outerportion of the coils may have a rounded profile, (f) an outer portion ofthe coils may have a radius of curvature of 44 mm under its own weightwhen draped over a cylinder having a 13 mm diameter, (g) an outerportion of the coils may have an oval-shaped profile, (h) the coils mayhave a greater thickness than the web of material, (i) the web ofmaterial may have a substantially uniform thickness, (j) the coils maycomprise a thermoplastic elastomer, (k) the web of material may comprisea thermoplastic elastomer, (l) the web of material and the coils may bebonded to form a uniform and continuous inner surface of the gasdelivery tube, (m) the web of material may comprise at least one foldextending radially outward between alternating ones of the plurality ofcoils, (n) the coils may have a pitch of about 3.2 mm to about 4.7 mm,(o) the coils may have a pitch of about 4.5 mm to about 4.7 mm, (p) thecoils may have a spring stiffness of about 0.03 N/mm, (q) an internaldiameter of the tube may be about 18 mm when in a neutral state, and/or(r) the gas delivery tube may comprise one of three different states: aneutral state wherein the gas delivery tube comprises a neutral length,an extended state wherein the gas delivery tube is extended to anextended length that is greater than the neutral length, and acompressed state wherein the gas delivery tube is compressed to acompressed length that less than the neutral length.

Another aspect of the present technology is directed to a respiratorytherapy system to supply breathable gas to a patient. The respiratorytherapy system may comprise: a respiratory mask assembly to be worn bythe user during therapy; a gas delivery tube according to at least oneof the examples described in the previous paragraph, said gas deliverytube fixedly attached at a first end to the respiratory mask assemblyand having a rotatable adapter fixedly attached to a second end; anadditional gas delivery tube being different from the gas delivery tuberotatably attached at a third end to the gas delivery tube by therotatable adapter; and/or a respiratory apparatus to generate a flow ofbreathable gas connected to said additional gas delivery tube at afourth end.

In accordance with another aspect of the present technology, there isprovided a patient interface for the treatment of respiratory disorders.The patient interface may comprise a rigidiser arm made from a firstmaterial. The patient interface may also comprise a flexible jointpermanently connected to the rigidiser arm, the flexible joint beingmade from a second material that is unable to be integrally bonded withthe first material. The patient interface may also comprise a mask framepermanently connected to the flexible joint, the mask frame being madefrom a third material that is integrally bonded with the secondmaterial. The rigidiser arm and the flexible joint may be permanentlyconnected by way of a mechanical interlock. The first material, thesecond material, and the third material may be distinct materials.

The integral bond may be a covalent bond or hydrogen bond.

The first material may be a thermoplastic polyester elastomer. Thethermoplastic polyester elastomer may be Hytrel® 5556 manufactured byDuPont®.

The second material may be a thermoplastic elastomer (TPE). The TPE maybe Dynaflex™ TPE compound or Medalist® MD-115.

The third material may be a thermoplastic polymer. The thermoplasticpolymer may be polypropylene (PP).

The flexible joint may be overmolded to the mask frame.

The mechanical interlock may comprise a protrusion extending from therigidiser arm that is overmolded by the material of the flexible joint.The protrusion may be T-shaped having a void in a central region of theprotrusion which extends through a top side to a bottom side of theprotrusion for material of the flexible joint to pass therethrough.

The mechanical interlock may comprise two protrusions extendinglaterally from a distal end of the rigidiser arm,

Next to each protrusion may be a void which extends through therigidiser arm for material of the flexible joint to pass therethrough.

The patient interface may be nasal pillows or a nasal cradle.

In accordance with another aspect of the present technology, there isprovided a patient interface for the treatment of respiratory disorders.The patient interface may comprise a rigidiser arm made from a firstmaterial. The patient interface may also comprise a mask framepermanently connected to the rigidiser arm. The mask frame may be madefrom a second material that is unable to be integrally bonded with thefirst material. The first material may be relatively more resilientlyflexible than the second material. The rigidiser arm and the mask framemay be permanently connected by way of a mechanical interlock.

The mask frame may be overmolded to the rigidiser arm.

The mechanical interlock may comprise an enclosable section extendingfrom the rigidiser arm that is overmolded by the material of the maskframe.

The enclosable section may have a portion of a bend and a hook.

In accordance with another aspect of the present technology, there isprovided a patient interface for the treatment of respiratory disorders.The patient interface may comprise a rigidiser arm made from a firstmaterial. The patient interface may also comprise a mask frame made froma second material and may be integrally bonded to the rigidiser arm. Thefirst material may be relatively more resiliently flexible than thesecond material. The first material may be a fiber reinforced compositepolypropylene material and the second material is polypropylene.

The fiber reinforced composite polypropylene material may be Curv®.

In accordance with another aspect of the present technology, there isprovided a patient interface for the treatment of respiratory disorders.The patient interface may comprise a rigidiser arm. The patientinterface may also comprise a mask frame releasably engageable with therigidiser arm. The rigidiser may be more resiliently flexible than themask frame. The rigidiser arm may include a protruding end configured toretain a pocketed end of a strap of a positioning and stabilisingstructure. The protruding end may be proximal to the mask frame.

The patient interface may further comprise a flexible joint releasablyengageable with the rigidiser arm. The flexible joint may also bereleasably engageable with the mask frame. The flexible joint may berelatively more resiliently flexible than the rigidiser arm.

The releasable engagement between the rigidiser arm and the mask framemay be provided by a mechanical clip assembly.

The releasable engagement between the flexible joint and the rigidiserarm, and between the flexible joint and the mask frame may be providedby a mechanical clip assembly.

Another aspect of the present technology is directed to a patientinterface for the treatment of respiratory disorders. The patientinterface may comprise a rigidiser arm that may be made from a firstmaterial that may not be stretchable; a mask frame may be permanentlyconnected to the rigidiser arm, the mask frame may be made from a secondmaterial that may be unable to be integrally bonded with the firstmaterial; the first material may be relatively more resiliently flexiblethan the second material, and the rigidiser arm and the mask frame maybe permanently connected by way of a mechanical interlock, and therigidiser arm may be made from the first material and may be permanentlyconnected to the mask frame such that, when the patient interface isdonned by a patient, the rigidiser arm may be structured such that it isflexible only in a plane substantially parallel to a patient's Frankforthorizontal.

In examples, (a) the mask frame may be overmolded to the rigidiser arm,(b) the mechanical interlock may comprise an enclosable sectionextending from the rigidiser arm that is overmolded by the material ofthe mask frame, and/or (c) the enclosable section may have a portion ofa bend and a hook.

Another aspect of the present technology is directed to a rigidiser armto operatively connect an elastic fabric strap of a positioning andstabilising structure to a mask frame. The rigidiser arm may comprise amain body that may have a curvature to substantially follow a cheekshape of a patient; a protruding end may be configured to retain apocketed end of the strap, the protruding end may be located at a distalend of the rigidiser arm; a connection portion may be configured toconnect to a flexible joint or a mask frame, the connection portion maybe located at the distal end of the rigidiser arm.

In examples, (a) the connection portion may comprise at least oneprotrusion and at least one void configured to be overmolded to connectto the flexible joint or the mask frame, (b) the rigidiser arm maycomprise a thermoplastic polyester elastomer, (c) the rigidiser arm maycomprise a material wherein the rigidiser arm is flexible within onlyone plane, and/or (d) the rigidiser arm may comprise a material thatdoes not stretch. Another aspect of the present technology is directedto a patient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The patientinterface may comprise: a cushion member that includes a retainingstructure and a pair of nasal pillows pneumatically connected to aplenum chamber by stalks permanently connected to the retainingstructure; and a frame member, wherein the retaining structure and theframe member are repeatedly engageable with and disengageable from oneanother; and wherein opposing sides of each stalk have unequal materialstiffness to provide increased resistance to deformation of the stalk ina direction opposite a predetermined direction.

Another aspect of the present technology is directed to a patientinterface for delivery of a supply of pressurised air or breathable gasto an entrance of a patient's airways. The patient interface maycomprise: a cushion member that includes a retaining structure and aseal-forming structure permanently connected to the retaining structure;and a frame member, wherein the retaining structure and the frame memberare repeatedly engageable with and disengageable from one another;wherein the seal-forming structure has a greater length than theretaining structure in a direction parallel to a direction of engagementand disengagement between the retaining structure and the frame member;and wherein the cushion member has a first thickness proximal to theretaining structure and a second thickness that is less than the firstthickness proximal to the seal-forming structure, and the thickness ofthe cushion member is gradually reduced from the first thickness to thesecond thickness.

Another aspect of the present technology is directed to a patientinterface system to provide breathable gas to a patient. The patientinterface may comprise: a patient interface including a seal-formingstructure to provide a pneumatic connection to a patient's airways; anda positioning and stabilising structure including at least one strap andat least one rigidiser arm and configured to releasably retain thepatient interface on the patient, wherein the at least one rigidiser armhas a bend to redirect the longitudinal axis of the at least onerigidiser arm from a first plane substantially parallel to the sagittalplane to a second plane substantially parallel to the coronal plane.

Another aspect of the present technology is directed to a patientinterface for the treatment of respiratory disorders. The patientinterface may comprise: a washable and re-usable vent to washout exhaledair having a thickness no greater than 0.45 mm and a weight no greaterthan 234 grams per m²; wherein the vent has a porous region that definesa tortuous air flow path for the exhaled air and the porous region has apredetermined level of stiffness to substantially maintain its shapeduring breathing cycles of a patient.

Another aspect of the present technology is directed to a cushion memberfor a patient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The cushion membermay comprise: a retaining structure for repeatable engagement with anddisengagement from a frame member; and a seal-forming structurepermanently connected to the retaining structure; wherein theseal-forming structure is made from a first material and the retainingstructure is made from a second material with different mechanicalcharacteristics from the first material and the second material is morerigid than the first material; and wherein an increase in air pressurewithin the cushion member causes a sealing force between theseal-forming structure and the frame member to increase.

Another aspect of the present technology is directed to a gas deliverytube for delivery of a supply of pressurised air or breathable gas to anentrance of a patient's airways via a patient interface. The gasdelivery tube may comprise: a helical coil comprised of a plurality ofadjacent coils, each coil separated by a width; a web of materialcoaxial to the helical coil attached to the helical coil betweenadjacent ones of the plurality of adjacent coils and having at least onefold extending radially outward between adjacent ones of the pluralityof adjacent coils, said at least one fold defined by a predeterminedfold line; a first end cuff for permanently and non-rotatably connectingthe tube to a frame of the patient interface; a second end cuff forreleasably and rotatably connecting with a tube adapter; wherein the gasdelivery tube comprises one of three different states: a neutral statewherein the gas delivery tube comprises a neutral length, an extendedstate wherein the gas delivery tube is extended along its longitudinalaxis to an extended length that is greater than the neutral length, anda compressed state wherein the gas delivery tube is compressed along itslongitudinal axis to a compressed length that is less than the neutrallength.

Another aspect of the present technology is directed to a cushion memberfor a patient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The cushion membermay comprise: a retaining structure for repeatable engagement with anddisengagement from a frame member; and a seal-forming structurepermanently connected to the retaining structure; wherein theseal-forming structure is made from a first material and the retainingstructure is made from a second material that is different from thefirst material and is more rigid than the first material; and whereinthe first material permits the seal-forming structure to readily conformto finger pressure and the second material prevents the retainingstructure from readily conforming to finger pressure.

Another aspect of the present technology is directed to a cushion memberfor a patient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The cushion membermay comprise: a retaining structure for repeatable engagement with anddisengagement from a frame member; and a seal-forming structureconnected to the retaining structure; wherein the seal-forming structureis made from a first material and the retaining structure is made from asecond material that is different from the first material and is morerigid than the first material; and wherein the retaining structure has acontinuous peripheral edge on an anterior side that contacts the framemember.

Another aspect of the present technology is directed to a rigidiser armto connect a strap of a positioning and stabilising structure to a maskframe. The rigidiser arm may comprise: a main body having a curvature inmore than one axis to substantially follow a cheek shape of a patient;wherein the rigidiser arm extends from a mask frame to a positionproximal to the cheekbone of the patient.

Another aspect of the present technology is directed to a patientinterface for delivery of a supply of pressurised air or breathable gasto an entrance of a patient's airways. The patient interface maycomprise: a mask frame having a vent orifice defined in the mask frame;a vent cap made from a plastic material removably engageable with themask frame at the vent orifice; and a vent permanently connected to thevent cap, the vent having a porous region for washout of exhaled air;wherein the vent is made from a textile formed by interlacing plasticfibers and a tortuous air path for the exhaled air is defined by spacesbetween the interlaced plastic fibers; and wherein the textile isstructured such that the shape, geometry and profile of the vent issubstantially unchanged during breathing cycles of the patient and theporous region maintains a substantially constant rate of washout for theexhaled air.

Another aspect of the present technology is directed to a vent cap for apatient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The vent cap maycomprise: a vent frame to removably engage with a vent orifice of a maskframe of the patient interface; and a vent permanently connected to thevent frame, the vent having a porous region for washout of exhaled air;wherein the vent is made from a textile formed by interlacing plasticfibers and a tortuous air path for the exhaled air is defined by spacesbetween the interlaced plastic fibers; and wherein the textile isstructured such that the shape, geometry and profile of the vent issubstantially unchanged during breathing cycles of the patient and theporous region maintains a substantially constant rate of washout for theexhaled air.

Another aspect of the present technology is directed to a vent for apatient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways. The vent maycomprise: an interlaced structure of fibers having tortuous air pathsfor exhaled air that are defined by spaces between the interlacedfibers; wherein the interlaced structure of fibers is configured tosubstantially maintain its shape, geometry and profile during breathingcycles of the patient and the spaces maintain a substantially constantrate of washout for the exhaled air.

Another aspect of the present technology is directed to a patientinterface to provide breathable gas to a patient, the patient interfacecomprising: a connection port; at least two vents; a first vent of theat least two vents on a first side of the connection port; and a secondvent of the at least two vents on a second side of a connection port,wherein the vent is a multi-hole vent or interlaced structure.

Another aspect of the present technology is directed to a cushion memberfor a patient interface for delivery of a supply of pressurised air orbreathable gas to an entrance of a patient's airways, said patientinterface including a frame connectable to the cushion member. Thecushion member may comprise: an visual indication indicator to preventmisalignment of the cushion member when the cushion member is connectedto the frame.

Another aspect of the present technology is directed to a gas deliverytube to supply a pressurised flow of breathable gas from a respiratoryapparatus. The gas delivery tube may comprise: a helical coil comprisedof a plurality of adjacent coils, each coil separated by a width andhaving an outer surface defining a coil diameter; and a web of materialcoaxial to the helical coil attached to the helical coil betweenadjacent ones of the plurality of adjacent coils and having at least onefold extending radially outward between adjacent ones of the pluralityof adjacent coils, said at least one fold defined by a predeterminedfold line, wherein a vertex of said at least one fold defines a folddiameter, wherein when the gas delivery tube is in a neutral state thecoil diameter being substantially equal to the fold diameter and theadjacent coils are separated from each other in the neutral state; andthe helical coil and the web of material are made from a thermoplasticmaterial; wherein the helical coil and the web or of material arestructured so that the gas delivery tube is prevented from occlusionoccluding during supply of the pressurised flow of breathable gas fromthe respiratory apparatus, and wherein the gas delivery tube has aflexural stiffness that is sufficiently low such that when a distal endof the gas delivery tube is elongated extended by thirty millimeters ina direction perpendicular to the orientation of a proximal end of thegas delivery tube, there is substantially no torsional tube drag at theproximal end.

Another aspect of the present technology is directed to a cushion memberfor a nasal pillows mask, nasal cradle mask or nasal mask for deliveryof a supply of pressurised air or breathable gas to an entrance of apatient's airways. The cushion member may comprise: a retainingstructure for repeatable engagement with and disengagement from a framemember; and a seal-forming structure permanently connected to theretaining structure; wherein an increase in air pressure within thecushion member causes a sealing force between the seal-forming structureand the frame member to increase; and wherein a retention force betweenthe retaining structure and the frame member is higher than adisengagement force to disengage the retaining structure from the framemember.

Another aspect of the present technology is directed to a patientinterface for delivery of a supply of pressurised air or breathable gasto an entrance of a patient's airways. The patient interface comprise: acushion member that includes a retaining structure and a seal-formingstructure permanently connected to the retaining structure; and a framemember, wherein the retaining structure and the frame member arerepeatedly engageable with and disengageable from one another; andwherein the retaining structure has a major axis with a length of about50 to 60 millimeters and a minor axis with a length of about 25 mm toabout 35 mm.

Another aspect of one form of the present technology is a patientinterface that is moulded or otherwise constructed with a clearlydefined perimeter shape which is intended to match that of an intendedwearer (i.e. patient) and be intimate and conform with the face of theintended wearer.

An aspect of one form of the present technology is a method ofmanufacturing the patient interface.

Of course, portions of the aspects may form sub-aspects of the presenttechnology. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present technology.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

Treatment Systems

FIG. 1a shows a system in accordance with the present technology. Apatient 1000 wearing a patient interface 3000, receives a supply of airat positive pressure from a PAP device 4000. Air from the PAP device4000 is humidified in a humidifier 5000, and passes along an air circuit4170 to the patient 1000.

FIG. 1b shows a PAP device 4000 in use on a patient 1000 with a nasalmask.

FIG. 1c shows a PAP device 4000 in use on a patient 1000 with afull-face mask.

Therapy Respiratory System

FIG. 2a shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

FIG. 2b shows a view of a human upper airway including the nasal cavity,nasal bone, lateral nasal cartilage, greater alar cartilage, nostril,lip superior, lip inferior, larynx, hard palate, soft palate,oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

Facial Anatomy

FIG. 2c is a front view of a face with several features of surfaceanatomy identified including the lip superior, upper vermillion, lowervermillion, lip inferior, mouth width, endocanthion, a nasal ala,nasolabial sulcus and cheilion.

FIG. 2d is a side view of a head with several features of surfaceanatomy identified including glabella, sellion, pronasale, subnasale,lip superior, lip inferior, supramenton, nasal ridge, otobasion superiorand otobasion inferior. Also indicated are the directions superior &inferior, and anterior & posterior.

FIG. 2e is a further side view of a head. The approximate locations ofthe Frankfort horizontal and nasolabial angle are indicated.

FIG. 2f shows a base view of a nose.

FIG. 2g shows a side view of the superficial features of a nose.

FIG. 2h shows subcutaneal structures of the nose, including lateralcartilage, septum cartilage, greater alar cartilage, lesser alarcartilage and fibrofatty tissue.

FIG. 2i shows a medial dissection of a nose, approximately severalmillimeters from a sagittal plane, amongst other things showing theseptum cartilage and medial crus of greater alar cartilage.

FIG. 2j shows a front view of the bones of a skull including thefrontal, temporal, nasal and zygomatic bones. Nasal concha areindicated, as are the maxilla, mandible and mental protuberance.

FIG. 2k shows a lateral view of a skull with the outline of the surfaceof a head, as well as several muscles. The following bones are shown:frontal, sphenoid, nasal, zygomatic, maxilla, mandible, parietal,temporal and occipital. The mental protuberance is indicated. Thefollowing muscles are shown: digastricus, masseter sternocleidomastoidand trapezius.

FIG. 2l shows an anterolateral view of a nose.

PAP Device and Humidifier

FIG. 3a shows an exploded view of a PAP device according to an exampleof the present technology.

FIG. 3b shows a perspective view of a humidifier in accordance with oneform of the present technology.

FIG. 3c shows a schematic diagram of the pneumatic circuit of a PAPdevice in accordance with one form of the present technology. Thedirections of upstream and downstream are indicated.

Patient Interface

FIG. 4 is an anterior view of a plenum chamber in accordance with oneform of the present technology.

FIG. 5 is a cross section along line 5-5 of FIG. 4.

FIG. 6 is an enlarged detail view taken from FIG. 5.

FIG. 7 is a perspective view from the top of the plenum chamber shown inFIG. 4.

FIG. 8 is a cross-section along line 8-8 of FIG. 7.

FIG. 9 is an enlarged detail view taken from FIG. 8.

FIG. 10 is a perspective view from the front side of a plenum chamberaccording to one example of the present technology.

FIG. 11 is a view of the plenum chamber shown in FIG. 4.

FIG. 12 is a cross-section taken along line 12-12 of FIG. 11.

FIG. 13 is an enlarged detail view taken from FIG. 12.

FIG. 14 is an enlarged cross-sectional view of the plenum connectionregion.

FIG. 15 is a side view of the patient interface shown in FIG. 11.

FIG. 16 is a cross-section taken along line 16-16 of FIG. 15.

FIG. 17 is an enlarged detail view taken from FIG. 16.

FIG. 18 is a side view of a patient interface in position on a modelpatient's head without any positioning and stabilising structure shown.

FIG. 19 is a partial, inferior view of a portion of a patient interfacein position on a model patient's head accordance with one form of thepresent technology. Note that only a portion of the positioning andstabilising structure connecting to the frame is shown for clarity.

FIG. 20 is a side view of a plenum connection region of a plenum chamberin accordance with one form of the present technology.

FIG. 21 is a view of a superior portion thereof.

FIG. 22 is an anterior view thereof.

FIG. 23 is an inferior view thereof.

FIG. 24 is a perspective view thereof.

FIG. 25 is a cross-sectional view of the connection portion and theframe connection region, wherein the plenum chamber and the frame arenot engaged.

FIG. 26 is a cross-sectional view of the connection portion and theframe connection region, wherein the plenum chamber and the frame are incontact but not fully engaged.

FIG. 27 is a cross-sectional view of the connection portion and theframe connection region, wherein the plenum chamber and the frame arenearly in full engagement with another such that the retention featureis deflected.

FIG. 28 is a cross-sectional view of the connection portion and theframe connection region, wherein the plenum chamber and the frame areengaged but separated such that the retention feature is deflected.

FIG. 29 is a cross-sectional view of the connection portion and theframe connection region, wherein the plenum chamber and the frame arefully engaged.

FIG. 30 is a rear perspective view of a patient interface according toan example of the present technology with the plenum chamber andseal-forming structure detached.

FIG. 31 is a front perspective view of a patient interface according toan example of the present technology with the plenum chamber andseal-forming structure detached.

FIG. 32 is a rear view of a patient interface according to an example ofthe present technology with the plenum chamber and seal-formingstructure detached.

FIG. 33 is a side view of a patient interface according to an example ofthe present technology with the plenum chamber and seal-formingstructure detached.

FIG. 34 shows a perspective view of a patient interface according toanother example of the present technology indicating the attachment ofan exemplary seal-forming structure and plenum chamber to a frame of thepatient interface.

FIG. 35 shows a cross-sectional view of a patient interface including amask frame, a flexible joint, and a rigidiser arm according to anexample of the present technology.

FIG. 36 shows a perspective view of a patient interface including a maskframe, a flexible joint, and a rigidiser arm according to an example ofthe present technology.

FIG. 37 shows an exploded view of a patient interface including a maskframe, a flexible joint, and a rigidiser arm according to an example ofthe present technology.

FIG. 38 shows a detailed view of an end of a rigidiser arm according toan example of the present technology.

FIG. 39 shows a perspective view of a patient interface including a maskframe, flexible joints, and rigidiser arms according to an example ofthe present technology.

FIG. 40 shows a cross-sectional view of a patient interface including amask frame, flexible joints, and rigidiser arms according to an exampleof the present technology.

FIG. 41 shows a perspective view of a rigidiser arm according to anexample of the present technology.

FIG. 42 shows a cross-sectional view of a patient interface including amask frame, a flexible joint, and a rigidiser arm according to anexample of the present technology.

FIG. 43 shows a perspective view of a patient interface including a maskframe, a flexible joint, and a rigidiser arm according to an example ofthe present technology.

FIG. 44 shows an exploded view of a patient interface including a maskframe, a flexible joint, and a rigidiser arm according to an example ofthe present technology.

FIG. 45 shows a detailed view of an end of a rigidiser arm according toan example of the present technology.

FIG. 46 shows a detailed view of an end of a rigidiser arm and aflexible joint according to an example of the present technology.

FIG. 47 shows a cross-sectional view of a rigidiser and a mask frameaccording to an example of the present technology.

FIG. 48 shows a detailed cross-sectional view of a rigidiser arm andmask frame according to an example of the present technology.

FIG. 49 shows a cross-sectional view of rigidiser arms and a mask frameaccording to an example of the present technology.

FIG. 50 shows a perspective view of rigidiser arms and a mask frameaccording to an example of the present technology.

FIG. 51 shows a detailed perspective view of the connection between arigidiser and a mask frame according to an example of the presenttechnology.

FIG. 52 shows a top view of rigidiser arms and a mask frame according toan example of the present technology, and in broken line indicatesflexing of the rigidiser arm in a laterally outwards direction in thecoronal plane.

FIG. 53 shows a detailed top view of the connection between a rigidiserand a mask frame according to an example of the present technology.

FIG. 54 shows a cross-sectional perspective view of rigidiser arms and amask frame according to an example of the present technology.

FIG. 55 shows a side view of a rigidiser and a mask frame according toan example of the present technology, and in broken line indicatesflexing of the rigidiser arm in a vertically downward direction in thesagittal plane.

FIG. 56 shows a front view of a rigidiser and a mask frame according toan example of the present technology.

FIG. 57 shows a perspective view of rigidiser arms and a mask frameaccording to an example of the present technology.

FIG. 58 shows a partially exploded perspective view of rigidiser armsand a mask frame according to an example of the present technology.

FIG. 59 shows a detailed and partially exploded perspective view of arigidiser and a mask frame according to an example of the presenttechnology.

FIG. 60 shows a perspective view of a rigidiser according to an exampleof the present technology.

FIG. 61 shows a view of a rigidiser arm according to an example of thepresent technology plotted on a grid in an X-Y plane.

FIG. 62 shows a view of a rigidiser arm according to an example of thepresent technology plotted on a grid in an X-Z plane.

FIG. 63 shows a view of a rigidiser arm according to an example of thepresent technology plotted on a grid in a Y-Z plane.

FIG. 64 shows a view of a rigidiser arm according to an example of thepresent technology plotted in three dimensions.

FIG. 65 shows a schematic perspective view of a positioning andstabilising structure in accordance with an example of the presenttechnology.

FIG. 66 shows a cross-sectional view of a positioning and stabilisingstructure taken along line 66-66 in FIG. 65.

FIG. 67 shows a schematic side view of an exemplary rigidiser arm for apositioning and stabilising structure in accordance with the presenttechnology.

FIG. 68 shows a schematic perspective view of an exemplary positioningand stabilising structure containing a rigidiser arm in accordance withthe present technology in a first state.

FIG. 69 shows a schematic perspective view of an exemplary positioningand stabilising structure containing a rigidiser arm in accordance withthe present technology in a second state.

FIG. 70 shows a schematic perspective view of an exemplary positioningand stabilising structure containing a rigidiser arm in accordance withthe present technology in a third state.

FIG. 71 shows a perspective view of an exemplary positioning andstabilising structure in accordance with the present technology donnedon a patient.

FIG. 72 shows a front view of an exemplary positioning and stabilisingstructure in accordance with the present technology donned on a patient.

FIG. 73 shows a side view of an exemplary positioning and stabilisingstructure in accordance with the present technology donned on a patient.

FIG. 74 shows a perspective view of an exemplary positioning andstabilising structure in accordance with the present technology donnedon a patient.

FIG. 75 shows a front view of an exemplary positioning and stabilisingstructure in accordance with the present technology donned on a patient.

FIG. 76 shows a side view of an exemplary positioning and stabilisingstructure in accordance with the present technology donned on a patient.

FIG. 77 shows a downward perspective view of an exemplary positioningand stabilising structure in accordance with the present technologydonned on a patient.

FIG. 78 shows a graph of the extension (in mm) of a strap of apositioning and stabilising structure according to an example of thepresent technology subjected to a range of loads (in Newtons).

FIG. 79 shows a top view of a strap of a positioning and stabilisingstructure according to an example of the present technology during anintermediate stage of production.

FIG. 80 shows a cross-sectional view taken through line 80-80 of FIG. 79of a strap of a positioning and stabilising structure according to anexample of the present technology during an intermediate stage ofproduction.

FIG. 81 shows a top view of a strap of a positioning and stabilisingstructure according to an example of the present technology.

FIG. 82 shows a top detailed view of a strap of a positioning andstabilising structure according to an example of the present technology.

FIG. 83 shows a cross-sectional view taken through line 83-83 of FIG. 81of a strap of a positioning and stabilising structure according to anexample of the present technology.

FIGS. 84 to 88 show a sequence of perspective views of a patient donninga positioning and stabilising structure according to an example of thepresent technology.

FIGS. 89 to 93 show a sequence of side views of a patient donning apositioning and stabilising structure according to an example of thepresent technology.

FIGS. 94 to 98 show a sequence of front views of a patient donning apositioning and stabilising structure according to an example of thepresent technology.

FIGS. 99 to 104 show a sequence of side views of a patient donning apositioning and stabilising structure according to an example of thepresent technology.

FIGS. 105 to 107 show a sequence of perspective views of a patientadjusting a patient interface according to an example of the presenttechnology.

FIGS. 108 to 112 show a sequence of rear views of a patient adjusting apositioning and stabilising structure according to an example of thepresent technology.

FIG. 113 shows a detailed view of the connection between a strap and arigidiser arm of a positioning and stabilising structure according to anexample of the present technology.

FIG. 114 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 115 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 116 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 117 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 118 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 119 shows a detailed view of the connection between a strap and arigidiser arm of a positioning and stabilising structure according to anexample of the present technology.

FIG. 120 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 121 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 122 shows another detailed view of the connection between a strapand a rigidiser arm of a positioning and stabilising structure accordingto an example of the present technology.

FIG. 123 shows a detailed view of a split region of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 124 shows another detailed view of a split region of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 125 shows another detailed view of a split region of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 126 shows a detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 127 shows another detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 128 shows another detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 129 shows another detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 130 shows another detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 131 shows another detailed view of a bifurcation of a strap of apositioning and stabilising structure according to an example of thepresent technology.

FIG. 132 shows a perspective view of a positioning and stabilisingstructure manufactured according to an example of the presenttechnology.

FIG. 133 shows a process of forming a positioning and stabilisingstructure straps from a continuous roll according to an example of thepresent technology.

FIG. 134 shows a conventional example depicting a knitting processaccording to an example of the present technology.

FIG. 135 shows a conventional example depicting a knitting processaccording to an example of the present technology.

FIG. 136 illustrates a basic warp knitted fabric according to an exampleof the present technology.

FIG. 137 is a schematic representation of the basic warp knitted fabricof FIG. 136.

FIG. 138 illustrates a basic warp knitted fabric according to an exampleof the present technology.

FIG. 139 illustrates a basic weft knitted fabric according to an exampleof the present technology.

FIG. 140 is a side view of a positioning and stabilising structurepositioned on a patient's head in accordance with an example of thepresent technology.

FIG. 141 shows the changing direction of the course or grain of thepositioning and stabilising structure of FIG. 140 according to anexample of the present technology.

FIG. 142 illustrates an increased stretch in the direction of the courseof a knitted positioning and stabilising structure according to anexample of the present technology.

FIG. 143 shows 3D printed links used to form a positioning andstabilising structure according to an example of the present technology

FIG. 144 shows a 3D printed positioning and stabilising structure pieceincluding a rigidiser according to an example of the present technology.

FIG. 145 shows a 3D printed positioning and stabilising structure strapsand clips according to an example of the present technology.

FIG. 146 shows a rear perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 147 shows a front perspective view of a vent for a patientinterface in accordance with one form of the present technology.

FIG. 148 shows a rear perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 149 shows a side perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 150 shows a side perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 151 shows a side perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 152 shows a top perspective view of a vent for a patient interfacein accordance with one form of the present technology.

FIG. 153 is a process flow diagram depicting a method for manufacturinga patient interface for the treatment of respiratory disorders inaccordance with an example of the present technology.

FIG. 154 is a system diagram generally depicting equipment used forcarrying out the method of FIG. 153.

FIG. 155 is a top view of a textile depicting vent portions after heatstaking in accordance with an example of the present technology.

FIG. 156 is a magnified top view of a peripheral edge of a vent portionbefore heat staking in accordance with an example of the presenttechnology.

FIG. 157 is a magnified top view of a peripheral edge of a vent portionafter heat staking in accordance with an example of the presenttechnology.

FIG. 158 is a magnified sectional side view of a peripheral edge of avent portion before heat staking in accordance with an example of thepresent technology.

FIG. 159 is a magnified sectional side view of a peripheral edge of avent portion after heat staking in accordance with an example of thepresent technology.

FIG. 160 shows a short tube in a neutral state according to an exampleof the present technology.

FIG. 161 shows a side view of a short tube in a compressed stateaccording to an example of the present technology.

FIG. 162 shows a side view of a short tube in an elongated stateaccording to an example of the present technology.

FIG. 163 shows a side view of a short tube in a curved state accordingto an example of the present technology.

FIG. 164 shows a cross-sectional view of a short tube taken along line163-163 as shown in FIG. 163 according to an example of the presenttechnology.

FIG. 165 shows a perspective view of a short tube in a curved andelongated state according to an example of the present technology.

FIG. 166 is a perspective view showing a patient interface system inaccordance with one form of the present technology in use on a patient.

FIG. 167 is a chart depicting vertical plane air speed in m/s along thex and z axes from a vent of a SWIFT FX™ nasal pillows mask by ResMedLimited.

FIG. 168 is a chart depicting horizontal plane air speed in m/s alongthe x and y axes from a vent of a SWIFT FX™ nasal pillows mask by ResMedLimited.

FIG. 169 is a chart depicting vertical plane signal along the x and yaxes from a vent of a SWIFT FX™ nasal pillows mask by ResMed Limited.

FIG. 170 is a chart depicting horizontal plane signal along the x and yaxes from a vent of a SWIFT FX™ nasal pillows mask by ResMed Limited.

FIG. 171 is a chart depicting vertical plane air speed in m/s along thex and z axes from a vent of a patient interface system in accordancewith one form of the present technology.

FIG. 172 is a chart depicting horizontal plane air speed in m/s alongthe x and y axes from a vent of a patient interface system in accordancewith one form of the present technology.

FIG. 173 is a chart depicting vertical plane signal along the x and yaxes from a vent of a patient interface system in accordance with oneform of the present technology.

FIG. 174 is a chart depicting horizontal plane signal along the x and yaxes from a vent of a patient interface system in accordance with oneform of the present technology.

FIG. 175 is a chart comparing velocity (in m/s) along a vent axisaccording to distance (in mm) from a vent of a SWIFT FX™ nasal pillowsmask by ResMed Limited and a vent of a patient interface system inaccordance with one form of the present technology.

FIG. 176 is a bottom perspective view of a reinforcement portion foldedover the end of a strap of a positioning and stabilising structure inaccordance with one form of the present technology

FIG. 177 is a top planar view of a reinforcement portion folded over theend of a strap of a positioning and stabilising structure in accordancewith one form of the present technology.

FIG. 178 is a side perspective view of a reinforcement portion foldedover the end of a strap of a positioning and stabilising structure inaccordance with one form of the present technology.

FIG. 179 is a side planar view of a reinforcement portion folded overthe end of a strap of a positioning and stabilising structure inaccordance with one form of the present technology.

FIG. 180 is a magnified view of FIG. 179.

FIG. 181 is a magnified view of FIG. 177.

FIGS. 182 to 184 show a series of steps of removing a strap from arigidiser arm of a positioning and stabilising structure in accordancewith one form of the present technology.

FIGS. 185 and 186 show a series of steps of attaching a strap to arigidiser arm of a positioning and stabilising structure in accordancewith one form of the present technology.

FIG. 187 is a side planar view of a rigidiser arm of a positioning andstabilising structure in accordance with one form of the presenttechnology showing a visual indicator.

FIG. 188 is a side planar view of a rigidiser arm of a positioning andstabilising structure in accordance with one form of the presenttechnology showing a visual indicator.

FIG. 189 is a front planar view of fame and rigidiser arms in accordancewith one form of the present technology showing visual and tactileindicators.

FIG. 190 is a top planar view of a seal-forming structure in accordancewith one form of the present technology showing a visual indicator.

FIG. 191 is a rear planar view of a seal-forming structure in accordancewith one form of the present technology showing a visual indicator.

FIG. 192 is a top perspective view of a seal-forming structure inaccordance with one form of the present technology showing a visualindicator.

FIG. 193 is a cross-sectional view taken through line 193-193 of FIG.192.

FIG. 194 is a cross-sectional view taken through line 194-194 of FIG.192.

FIG. 195 is a rear planar view of a frame in accordance with one form ofthe present technology.

FIG. 196 is a top planar view of a frame in accordance with one form ofthe present technology.

FIG. 197 is a rear perspective view of a frame in accordance with oneform of the present technology.

FIG. 198 is a side planar view of a frame in accordance with one form ofthe present technology.

FIG. 199 is a rear planar view of a retaining structure of a plenumconnection region in accordance with one form of the present technology.

FIG. 200 is a bottom planar view of a retaining structure of a plenumconnection region in accordance with one form of the present technology.

FIG. 201 is a rear perspective view of a retaining structure of a plenumconnection region in accordance with one form of the present technology.

FIG. 202 is a side planar view of a retaining structure of a plenumconnection region in accordance with one form of the present technology.

FIGS. 203 to 207 show a tube in accordance with one form of the presenttechnology being elongated by a distance of 30 mm, 60 mm, 90 mm, and 120mm with a lower end of the tube held in a fixed position with itslongitudinal axis at its lower end being perpendicular to the directionof elongation before elongation commences.

FIGS. 208 to 212 show a ResMed™ Swift FX™ Nasal Pillows Mask tube beingelongated by a distance of 30 mm, 60 mm, 90 mm, and 120 mm with a lowerend of the tube held in a fixed position with its longitudinal axis atits lower end being perpendicular to the direction of elongation beforeelongation commences.

FIGS. 213 to 217 show a Philips™ Respironics™ GoLife™ Nasal Pillows Masktube being elongated by a distance of 30 mm, 60 mm, 90 mm, and 120 mmwith a lower end of the tube is held a fixed position with itslongitudinal axis at its lower end being perpendicular to the directionof elongation before elongation commences.

FIGS. 218 to 222 show a Philips™ Respironics™ Wisp™ Nasal Mask tubebeing elongated by a distance of 30 mm, 60 mm, 90 mm, and 120 mm with alower end of the tube held in a fixed position with its longitudinalaxis at its lower end being perpendicular to the direction of elongationbefore elongation commences.

DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

Treatment Systems

In one form, the present technology comprises apparatus for treating arespiratory disorder. The apparatus may comprise a flow generator orblower for supplying pressurised respiratory gas, such as air, to thepatient 1000 via an air circuit 4170 leading to a patient interface3000, as shown in FIG. 1 a.

Therapy

In one form, the present technology comprises a method for treating arespiratory disorder comprising the step of applying positive pressureto the entrance of the airways of a patient 1000.

Nasal CPAP for OSA

In one form, the present technology comprises a method of treatingObstructive Sleep Apnea in a patient by applying nasal continuouspositive airway pressure to the patient.

Patient Interface 3000

Referring to FIG. 166, a non-invasive patient interface 3000 inaccordance with one aspect of the present technology comprises thefollowing functional aspects: a seal-forming structure 3100 (see, e.g.,FIG. 4), a plenum chamber 3200, a positioning and stabilising structure3300 and a connection port 3600 for connection to a short tube 4180 ofthe air circuit 4170. In some forms a functional aspect may be providedby one or more physical components. In some forms, one physicalcomponent may provide one or more functional aspects. In use theseal-forming structure 3100 is arranged to surround an entrance to theairways of the patient 1000 so as to facilitate the supply of air atpositive pressure to the airways.

Seal-Forming Structure 3100

In one form of the present technology, the seal-forming structure 3100provides a sealing-forming surface, and may additionally provide acushioning function.

A seal-forming structure 3100 in accordance with the present technologymay be constructed from a soft, flexible, resilient material such assilicone. The seal-forming structure 3100 may form part of a sealed pathfor air from a PAP device to be delivered to the nares of the patient.

Referring to FIG. 9, in one form of the present technology, theseal-forming structure 3100 may comprise a sealing flange 3110 and asupport flange 3120. The sealing flange 3110 may comprise a relativelythin member with a thickness of less than about 1 mm, for example about0.25 mm to about 0.45 mm. The support flange 3120 may be relativelythicker than the sealing flange 3110. The support flange 3120 is orincludes a spring-like element and functions to support the sealingflange 3110 from buckling in use. In use the sealing flange 3110 canreadily respond to system pressure in the plenum chamber 3200 acting onits underside to urge it into tight sealing engagement with the face,e.g., the patient's nares. The plenum chamber 3200 is made from a floppymaterial such as silicone.

Nasal Pillows

In one form of the present technology, the seal-forming structure 3100of the non-invasive patient interface 3000 comprises a pair of nasalpuffs, or a pair of nasal pillows 3130, each nasal puff or nasal pillowbeing constructed and arranged to form a seal with a respective naris ofthe nose of a patient, e.g. by forming a seal against a peripheralregion of the nares of the patient.

Nasal pillows 3130 (FIG. 9) in accordance with an aspect of the presenttechnology include: a frusto-cone 3140, at least a portion of whichforms a seal on an underside of the patient's nose e.g. a frusto-coneportion; a stalk 3150, an upper flexible region 3142 on the underside ofthe frusto-cone 3140 and connecting the frusto-cone to the stalk 3150.In addition, the structure to which the nasal pillow 3130 of the presenttechnology is connected includes a lower flexible region 3152 adjacentthe base of the stalk 3150. Upper flexible region 3142 and lowerflexible region 3152 can act in concert to facilitate a universal jointstructure that is accommodating of relative movement—both displacementand angular—of the frusto-cone 3140 and the structure to which the nasalpillow 3130 is connected. In one example, the frusto-cone 3140 may beco-axial with stalk 3150 to which it is connected. In another example,the frusto-cone 3140 and the stalk 3150 may not be co-axial (e.g.,offset). The nasal pillows 3130 may be dimensioned and/or shaped suchthat they extend out laterally beyond the walls of the plenum chamber3200, discussed below.

In one form of the present technology, each stalk 3150 may comprise avariable stiffness so as to prevent the nasal pillows 3130 from rockingforward during use due to compression and/or bending of the stalk 3150.For example, the side of the stalk 3150 that is distal from the face ofthe patient in use may be stiffer than the region of the stalk 3150proximal to the face of the patient. In other words, different materialstiffness on opposing sides of the stalk 3150 presents more resistanceif compression or bending of the stalk 3150 is not in a predetermineddirection. This enables even compression of the pillows 3130 onto naresby preventing the pillows 3130 from rocking forward. Such an arrangementmay be helpful in resisting buckling of the stalk 3150 that results inthe nasal pillows 3130 rocking forward. The variable stiffness may alsobe used to provide a weak point about which rocking is facilitated suchthat the stalks 3150 buckle in a desired direction. In other words, evencompression of the nasal pillows 3130 may be achieved. This arrangementmay also allow the sealing force to be localized at the top of the nasalpillows 3130. Additionally, this arrangement may also allow anydeflection of the nasal pillows 3130 to be cantered thereon. The nasalpillows 3130 may also be formed to compress against the plenum chamber3200 when urged against the face of the patient and because the nasalpillows 3130 may be laterally wider than the plenum chamber, no portionof the plenum chamber 3200 extends beyond the pillows 3130. In anotherexample, when compressed, the nasal pillows 3130 may be shaped and/ordimensioned so that their periphery is generally flush with theperiphery of the plenum chamber 3200. In a further example of thetechnology, the stalks 3150 may be thinnest at the base of thefrusto-cone 3140.

In an example, to engage the pillows 3130 with the entrance to thepatient's airways, the pillows 3130 are placed at the entry to thenares. As the positioning and stabilising structure 3300 is adjusted,tension begins to pull the pillows 3130 into the nares. Continuedinsertion of the pillows 3130 into the nares causes the stalk 3150 tocollapse via trampoline 3131 moving the base of pillows 3130 towards theupper surface of the plenum chamber 3200. The stalks 3150 of the nasalpillows 3130 may be connected to the plenum chamber 3200 and comprisethinned, or reduced thickness, portions. The thinned portions allow thepillows 3130 to easily spring, or trampoline, and therefore adjust tosuit the alar angle of the patient 1000 more readily. The trampoline3131 may be angled away from the bottom of the pillows 3130 or a septumand/or upper lip of the patient 1000. This improves the comfort andstability of the patient interface device 3000.

It is also envisioned that a variety of sizes of nasal pillows 3130 maybe used with plenum chambers having a commonly sized connection regionand plenum connection region. This has the advantage of allowing thepatient to be fitted with a plenum chamber 3200 and pillows 3130 sizedto best fit that patient's particular anatomy, e.g., size andorientation of the nares.

In one form of the present technology the seal-forming structure 3100forms a seal at least in part on a columella region of a patient's nose.

Nasal Cushion

While a small portion of a nasal pillow 3130 may enter a nose in use, analternative form of seal-forming structure 3100 is substantiallyexternal of the nose in use. In one form of the present technology,shown in FIG. 34, the seal-forming structure 3100 of the non-invasivepatient interface 3000 is constructed and arranged to form a sealagainst the patient's airways that surrounds both nares without beingpartially located inside the nose. The seal-forming structure 3100serves both nares with a single orifice, e.g. a nasal cushion or nasalcradle. In FIG. 34 the seal-forming structure 3100 according to thedepicted example includes a nasal flange 3101 disposed about itsperiphery. This view also indicates the attachment of the plenum chamber3200 and seal-forming structure 3100 to the frame 3310.

Plenum Chamber 3200

Plenum chamber 3200 in accordance with an aspect of one form of thepresent technology functions to allow air flow between the two nares andthe supply of air from PAP device 4000 via a short tube 4180. The shorttube 4180 is typically part of the air circuit 4170 that connects to theframe 3310 via a connection port 3600 and a longer tube (additional gasdelivery tube) 4178 connected to the PAP device 4000. In this way theplenum chamber 3200 may function alternatively as an inlet manifoldduring an inhalatory portion of a breathing cycle, and/or an exhaustmanifold during an exhalatory portion of a breathing cycle.

Plenum chamber 3200 may be constructed from an elastomeric material.

Plenum chamber 3200, in accordance with another aspect of one form ofthe present technology, provides a cushioning function between theseal-forming structure 3100 and the positioning and stabilisingstructure 3300.

Whilst in one form of the plenum chamber 3200, the inlet/outlet manifoldand cushioning functions are performed by the same physical component,in an alternative form of the present technology, they are formed by twoor more components.

The seal-forming structure 3100 and the plenum chamber 3200 may beformed, e.g. moulded, as a single and unitary component.

Plenum chamber 3200 comprises an anterior wall 3210 and a posterior wall3220.

Posterior wall 3220 comprises posterior surface 3222 (see FIG. 8). Inone form of the present technology, the seal-forming structure 3100 isconstructed and arranged relative to the posterior wall 3220 so that inuse, the posterior surface 3222 is spaced from a patient's septum and/orupper lip, as can be seen in FIGS. 18 and 19. In one form, e.g. when theseal-forming structure 3100 includes nasal pillows 3130, this isachieved by arranging the posterior wall 3220 so that the posteriorsurface 3222 is anterior to a most posterior portion 3130.1 of the nasalpillow 3130, as shown in FIG. 8 by the posterior surface 3222. Thisarrangement may also focus the sealing force on the nares of the patient1000 because the septum and/or upper lip is relieved of contact with thepatient interface 3000.

The plenum chamber 3200 also comprises a flexing region 3230 (FIG. 9),which forms a connection with seal-forming structure 3100. The flexingregion 3230 may be a distinct region from the anterior wall 3210 and/orthe posterior wall 3220. Alternatively some or all of the respectiveanterior wall 3210 and posterior wall 3220 may form part of flexingregion 3230. In one form of the present technology where theseal-forming structure 3100 comprises respective left and right nasalpillows 3130, there is a corresponding respective left flexing region3232 and right flexing region 3234 (FIG. 4). Flexing regions 3230, 3232,and 3234 are constructed and arranged to bend and/or flex in response toa force encountered in use of the patient interface 3000, e.g., a tubedrag force, or a movement of the patient's head, e.g., pushing thepatient interface 3000 against a bed pillow. Flexing region 3230, leftflexing region 3232, and/or right flexing region 3234 may be constructedfrom a silicone rubber, e.g., with a Type A indentation hardness in therange of about 35 to about 45. However, a wider range is possible if thethickness of the walls 3210, 3220 are adjusted accordingly to obtain asimilar level of force.

Another aspect of the present technology that may be seen in FIGS. 4, 7,8, 10 and 11, that the plenum chamber 3200 has a saddle or decouplingregion 3236. As can be seen in FIG. 4, the flexing region 3230 maycomprise the decoupling region 3236, which may be located between theleft flexing region 3232 and the right flexing region 3234. Thedecoupling region 3236 may be concave in shape and may span from theanterior wall 3210 to the posterior wall 3220. By forming the plenumchamber 3200 with the decoupling region 3236 as described, it may bepossible to decouple the left flexing region 3232 from the right flexingregion 3234 such that movement in one of the flexing regions does notsubstantially affect the other flexing region. In other words,deformation and/or buckling of the left flexing region 3232 may notcause a disruption to the right flexing region 3234 and vice versa.Advantageously, this may allow the nasal pillow 3130 associated with theundisturbed flexing region to remain in position on the patient'scorresponding naris in spite of a disruption to the other flexingregion. The decoupling region 3236, by being recessed between the stalks3150, may avoid contact with the septum. Also, the decoupling region3236 may be the thinnest region of the plenum chamber 3200 to allow forthe desired amount of flexibility in this region. Alternatively, thedecoupling region 3236 may be the thickest region of the plenum chamber3200. By providing the saddle region 3236 with a deep curvature, septumand/or upper lip contact may be minimised or avoided to improve patientcomfort. The saddle region 3236 may be U or V shaped and has anasolabial angle at its peak of about 70° to about 120°. The saddleregion 3236 may be about 0.5 mm to about 2.5 mm in depth for clearancearound the patient's septum.

Posterior wall 3220 may be arranged, in use of patient interface 3000,adjacent the superior or upper lip of the patient, as in FIGS. 18 and19.

In one form, the plenum chamber 3200 may further comprise a sealing lip3250 (FIG. 6). Sealing lip 3250 may be constructed from a flexibleresilient material, e.g. silicone rubber with a type A hardness in arange of about 30 to about 50, forming a relatively soft component.Sealing lip 3250 may be located on or formed as part of an interiorsurface or interior periphery of plenum chamber 3200, or an entireinterior peripheral region of plenum chamber 3200, as shown in FIGS. 5,6 and 8. However, it is also envisioned that the sealing lip 3250 may bedisposed about an exterior surface or exterior periphery of the plenumchamber 3200, or an entire exterior peripheral region of plenum chamber3200. Sealing lip 3250 may form a pneumatic seal between plenum chamber3200 and frame 3310, as will be described in greater detail below.Sealing lip 3250 and plenum chamber 3200 may also comprise one piece.Other patient interface devices form the pneumatic seal between theplenum chamber and frame using a compression seal to compress the plenumchamber made from a resiliently deformable material such as silicone toengage the plenum chamber to the frame and create the pneumatic seal atthe same time. In contrast, one example of the present technology, formsa pneumatic seal when the plenum chamber 3200 is initially secured tothe frame 3100 by interference from the sealing lip 3250 deflectingagainst the frame 3310. When pressure within the plenum chamber 3200 isincreased above atmospheric pressure for treating breathing disorders,the pneumatic seal is strengthened and increases the sealing force asthe sealing lip 3250 is urged with greater force against the frame 3310.The air pressure within the cushion/plenum chamber of these otherpatient interface devices does not influence the sealing force betweenthe cushion and the frame. Also, these other patient interface deviceshave a cushion with side walls for engagement with the frame and sealinglips that are floppy because they readily conform to finger pressure,are not rigid, and are able to be stretched or bent elastically withlittle effort. In particular, due to the size and aspect ratio of anasal cushion being relatively large, this contributes to the floppinessof the cushion. The side walls for frame engagement are so floppy thatopposing sides of the cushion are able to be pinched together andbrought into contact with each other with very little finger force. Thisease of deformation of the side walls for frame engagement may be theprimary source of difficulty for patients with arthritic hands toquickly connect the cushion to the frame in these other patientinterfaces. It should also be understood that by forming the plenumchamber 3200 features discussed above with sufficient stiffness it maybe possible to improve the stability of the seal made by theseal-forming structure. Furthermore, it may be possible to vary thethickness of the plenum chamber 3200 such that it becomes thinner from aplenum connection region 3240 to the seal-forming structure 3100. In oneexample of the present technology, the plenum chamber 3200 may be about2-3 mm thick near or at the plenum connection region 3240, 1 mm thick ata point between the plenum connection region 3240 and the seal-formingstructure 3100, and 0.75 mm thick near or at the seal-forming structure3100. Forming the plenum chamber 3200 with these features may beaccomplished by injection molding manufacturing. This gradual reductionin thickness of the plenum chamber 3200 enables greater deformability ofsilicone material closer to the stalks 3150 and patient's nose toenhance comfort and reduce the likelihood of seal disruption.

Some nasal pillow patient interfaces have an assembled order of (i),plenum chamber, (ii) headgear connection, and (iii) seal-formingstructure. In contrast, one example of the patient interface 3000 of thepresent technology has an assembled order of (i) headgear connection,(ii) plenum chamber, and (iii) seal-forming structure.

This difference in arrangement means that headgear tension does notcause deformation of the plenum chamber 3200 and the seal-formingstructure 3100 which may lead to disruption of sealing forces.

Frame 3310

Frame 3310 functions as a central hub, as shown in FIGS. 4, 10, 75, 76and 166, to which the short tube 4180, plenum chamber 3200 andpositioning and stabilising structure 3300 are connected, either in aremovable fashion or a more permanent fashion.

FIGS. 31 to 33 also show various views of the frame 3310 connected tothe positioning and stabilising structure 3300, having straps 3301, viaa flexible joint 3305. These views show the frame 3310 without theplenum chamber 3200 and the seal-forming structure 3100. The connectionport 3600 and the vent 3400, both described in greater detail below, maybe disposed on the frame 3310.

In one example of the technology, the frame 3310 may be formed frompolypropylene.

In another example of the technology, the frame 3310 may be made in onesize but the plenum chamber 3200 and seal-forming structure 3100 may bemade in multiple sizes that are attachable to the single frame bycommonly sized connections features as described herein.

In an example of the technology the frame 3310 may be molded without anyundercuts such that it may be molded and then removed from the mold toolwithout flexing.

Connection Between Plenum Chamber and Frame

In one form of the present technology, plenum chamber 3200 is removablyattachable to frame 3310, e.g., to facilitate cleaning, or to change fora differently sized seal-forming structure 3100. This may permit theplenum chamber 3200 to be washed and cleaned more often than the frame3310 and short tube 4180. Also, it may permit the plenum chamber 3200 tobe washed and cleaned separately from the strap 3301. In an alternativeform, plenum chamber 3200 is not readily removable from frame 3310.

Plenum chamber 3200 may comprise the plenum connection region 3240 (FIG.6). A retaining structure 3242 of the plenum connection region 3240 hasa shape and/or configuration that is complementary to a shape and/orconfiguration of a corresponding frame connection region 3312 (FIG. 10).The retaining structure 3242 of the plenum chamber 3200 is more rigidthan the other parts of the plenum chamber 3200, and may be made fromthe same material as the frame 3310, for example, polypropylene orpolyamide such as Rilsan®. In other examples, the plenum connectionregion 3240 may be made from nylon, and the frame 3310 made frompolypropylene. Nylon, polyamide and polypropylene are not floppymaterials and do not readily conform to finger pressure. Therefore, whenthey are engaged to each other, there is an audible click and a hard tohard connection. The shape of the retaining structure 3242 is depictedin FIGS. 20 to 24 in the form resembling a parabolic cylinder orhyperbolic cylinder. The retaining structure 3242 is not stretchable andinextensible in order to maintain its general shape as it engages anddisengages from the frame 3310. The shape of the retaining structure3242 allows a slight degree of flexing but not to the extent thatopposite sides of the retaining structure 3242 are able to touch eachother if pinched together with finger pressure. In other words, theopposite sides of the retaining structure 3242 can only be brought intocontact together with significant pinching force intended by the patient1000 which would not occur under normal therapy circumstances. In theillustrated example, the top and bottom edges of the retaining structure3242 are able to be pinched closer together/more easily together thanthe side edges of the retaining structure 3242 using the same amount ofpinching force. As can be seen in FIG. 18, the curvature of the frame3310 and retaining structure 3242 is intended to follow the naturalcurvature of patient's upper lip and may avoid concentration of contactpressure on any specific point of the patient's upper lip such thatcontact pressure from headgear tension is evenly spread over thepatient's upper lip. This may minimise or eliminate skin breakdowncaused by prolonged concentrated contact pressure. Another advantage forthe curvature is that less material is required for the plenum chamber3200 compared to a flat frame. A flat frame would result in morematerial for the plenum chamber 3200 at the side edges in order for theplenum chamber 3200 to conform to the patient's upper lip. Less materialleads to an overall weight reduction for the patient interface 3000. Thecurvature also minimises any protrusion of the patient interface 3000 inthe anterior direction from the patient's face which improves theunobtrusiveness of the patient interface 3000. Also, the retainingstructure 3242 may be glued (e.g. using an adhesive) onto the plenumchamber 3200, according to an example of the technology, after molding.In another example, an integral chemical bond (molecular adhesion) maybe utilized between the retaining structure 3242 and the plenum chamber3200.

In an example of the technology, the retaining structure 3242 may bemolded without any undercuts such that it may be molded and then removedfrom the mold tool without flexing. The retaining structure 3242 has acontinuous peripheral edge on an anterior side that contacts the frame3310. This continuous peripheral edge is exposed so that it makescontact with the frame 3310 for engagement in a hard to hard manner.This is in contrast to a majority soft to hard connection where in someprior masks there is an anterior lip portion of the seal-formingstructure that covers and overlaps the majority of a detachable rigidretaining structure. The anterior lip portion is made from LSR and wrapsover the retaining structure to hold it together. However, in such priormasks, it is difficult and cumbersome to wrap the anterior lip portionover a detachable clip and possible for the clip to be misplaced whichwould then result in the inability of connecting the seal-formingstructure to the frame.

One purpose of the retaining structure 3242 is to align the plenumchamber 3200 when engaging with the frame 3310 because the shape of theretaining structure 3242 of the plenum chamber 3200 is retained(possibly at varied depths) in a space defined between the frameconnection region 3312 and interfering portion 3314 of the frame 3310(FIG. 29).

Another purpose of the retaining structure 3242 is to retain the plenumchamber 3200 to the frame 3310 by preventing relative lateral andvertical relative movement between these two parts. Plenum connectionregion 3240 may comprise at least one retention feature 3244, and theremay be at least one complementary frame connection region 3312. Plenumconnection region 3240 may comprise one or more retention features 3244(FIG. 10). In addition to preventing relative lateral and verticalmovement between the plenum chamber 3200 and the frame 3310, anotherpurpose of the retention features 3244 is to prevent relativelongitudinal movement between these two parts. The remaining portion ofplenum chamber 3200 may comprise a more flexible material than theretaining structure 3242 and plenum connection region 3240.

In one form, plenum connection region 3240 is constructed from a rigidor semi-rigid material, e.g. high durometer silicone or TPE, plastic,nylon, a temperature resistant material, polypropylene, and/orpolycarbonate. Plenum connection region 3240 may be constructed from adifferent material to other portions of plenum chamber 3200. For exampleplenum connection region 3240 may be a separate component that ispermanently connected, integrally bonded or mechanically interlockedwith connection portion 3202 (FIG. 10) of the plenum chamber 3200.Turning to FIG. 6, the connection portion 3202 of the plenum chamber3200 may has substantially the same thickness as the retaining structure3242 of the plenum connection region 3240. Plenum connection region 3240may include a tongue portion 3211 constructed and arranged to bematingly received by a channel portion 3211.1, e.g., a channel portionof a frame 3310. In this way, the channel portion 3211.1 may form amating feature for the tongue portion 3211, and vice versa. Also, thetongue portion 3211 and the channel portion 3211.1 may be dimensioned tomaximize the sealing surface area in this region.

Attachment and Removal of Plenum Chamber from Frame

The plenum chamber 3200 may be fixedly attached to the frame 3310, butit also may be removably attached to the frame 3310. FIG. 12 shows theplenum chamber 3200 in a connected position relative to the frame 3310.Plenum connection region 3240 includes in this example only tworetention features 3244, which are positioned on opposite sides of theconnection region 3240, e.g., on the posterior and anterior sides. FIGS.12 and 13 shows a cross-section that passes through both barbs 3246,while FIG. 17 shows another cross-section where the barbs 3246 are notpresent, forming e.g. a channel or groove 3211.1. The resilient barbs3246 are a type of snap-in compression-fit member to provide a highretention force (to prevent accidental disengagement) and also enablerelatively easy intentional removal. In FIG. 17, the plenum connectionregion 3240 and the frame 3310 simply fit together in a tongue andgroove like manner. The frame 3310 and retaining structure 3242 may beshaped so that the tongue portion 3211 and the channel portion 3211.1engage before the retention features 3244 engage with the frame. Thismay help align the retention features 3244 for connection.

Each retention feature 3244 may take the form of a barb 3246 (FIGS. 6and 13) having a leading surface 3246.1 and a trailing surface 3246.2.The leading surface 3246.1 is adapted to engage a lead-in surface 3312.1of the frame connection region 3312 of the frame 3310, as the plenumchamber 3200 and the frame 3310 are moved into engagement with oneanother. As the retention feature 3244 is pushed into position itdeforms. Also, upper and lower regions of the frame connection region3312 and interfering portion 3314 of the frame 3310 may also slightlydeform. Also, the retaining structure 3242 may also slightly deformespecially near the retention feature 3244 (for example, see broken linein FIGS. 27 and 28). Turning to FIGS. 195 to 198, deformation of theframe connection region 3312 and interfering portion 3314 of the frame3310 is controlled in terms of the amount of deformation permitted andalso the areas of where deformation is to occur through the use of ribs3294. In one example of the present technology, there are six ribs 3294spaced around and against the interfering portion 3314. The spacing andposition of the ribs 3294 limit the area of deformation of theinterfering portion 3314 to only the area proximal to the retentionfeatures 3244. The ribs 3294 may also abut and deform against the innersurface of the plenum connection region 3240 to provide a firmerengagement between the plenum connection region 3240 and the frameconnection region 3312 at these contact points when the plenum chamber3200 is engaged with the frame 3310. Turning to FIGS. 199 to 202, theplenum connection region 3240 of the plenum chamber 3200 has notches3295 to correspond with the ribs 3294. The notches 3295 are chamfers tominimise the friction of the plenum connection region 3240 against theribs 3294 during assembly of the plenum chamber 3200 with the frame3310. Once the barb 3246 is pushed in a sufficient amount, it snapsoutwards in a radial sense such that the barb 3246 assumes a retainedposition shown in FIG. 13. The snapping action results in an audiblesound to the user such as a re-assuring click sound, providing feedbackto the user or patient that a proper connection has been established. Inthe retained position, the trailing surface 3246.2 of the barb 3246engages with a retaining surface 3312.2 of the frame connection region3312, as shown in FIG. 13. This reassuring click sound may also befacilitated, in one example of the technology, by forming the plenumconnection region 3240 of sufficient stiffness, that stiffness beinggreatest near the plenum connection region 3240. This stiffness may beaccomplished by overmolding manufacturing.

As can be seen in FIG. 13, the surfaces of the barb 3246 and the frameconnection region 3312 are angled in certain manners to facilitatesliding connection between the plenum chamber 3200 and the frame 3310.For example, as stated above, the leading surface 3246.1 and the lead-insurface 3312.1 may be formed with angles corresponding to one anothersuch that these to surfaces may slidingly engage with one another withrelative ease. Similarly, the trailing surface 3246.2 and the retainingsurface 3312.2 may be angled relative to one another to help retain theframe 3310 and the plenum chamber 3200 once connected. The anglesbetween the trailing surface 3246.2 and the retaining surface 3312.2 areselected such that a pulling force applied, e.g., generally along theaxis of the nasal pillows 3130, is sufficient to cause the barb 3246 toflex inwardly to thereby release the plenum chamber 3200 from the frame3310. This pulling force does not require the patient 1000 to firstdeflect the barbs 3246 radially inwards, e.g., by squeezing the plenumchamber 3200 in an anterior-posterior direction. Rather, due to theangles involved, the radial deflection of the barbs 3246 occurs solelyas a result of the axial pulling force applied. In one example of thepresent technology, the plenum connection region 3240 is deflected anddisassembly of the plenum chamber 3200 from the frame 3310 is performedby pinching the plenum chamber 3200 and pulling the plenum chamber 3200away from the frame 3310.

As can be seen in FIG. 13, the plenum chamber 3200 is attached to theframe 3310 via the plenum connection region 3240 and the retentionfeature 3244 is engaged with the frame connection region 3312 by thebarb 3246. Also shown in this view, the retaining surface 3312.2 of theframe connection region 3312 and the trailing surface 3246.2 of the barb3246 are engaged and flush with one another. For the patient to detachthe plenum chamber 3200 from the frame 3310 the patient must pull theplenum chamber 3200 with respect to the frame 3310 with sufficient forceto overcome the resistance of the retaining surface 3312.2 against thetrailing surface 3246.2. In one example of the present technology,pinching the plenum chamber 3200 reduces the axial pulling forcerequired to detach the plenum chamber 3200 from the frame 3310. Thisresistance can be “tuned” or selectively adjusted to a desired level byvarying the angle at which these surfaces 3312.2, 3246.2 engage with oneanother. The closer to perpendicular these surfaces 3312.2, 3246.2 arewith respect to the direction of the force applied by the patient 1000to detach the plenum chamber 3200 from the frame 3310, the greater theforce required to cause the detachment. This angle is shown as β in FIG.14, where the trailing surface 3246.2 is angled with respect to anominal vertical axis 3246.4 (corresponding to axial pull direction ofplenum chamber 3200 to the frame 3310). As β is increased, the forcerequired to detach the plenum chamber 3200 from the frame 3310 rises.Furthermore, as β increases the detachment will feel more abrupt to thepatient 1000. In one example, an angle β of approximately 75 degrees hasbeen found to generate a comfortable feel of detachment for the patient.In further examples, β may vary from 30 to 110 degrees or from 40 to 90degrees or from 65 to 85 degrees to generate an ideal level ofresistance to detachment. This has been selected to minimise thelikelihood of accidental detachment, and to only permit intentionaldetachment by the patient 1000.

Angle α, the angle between the nominal vertical axis 3246.4 and theleading surface 3246.1, can likewise be “tuned” or selectively adjustedto require a specific level of force when the patient 1000 attaches theplenum chamber 3200 to the frame 3310. As angle α is increased, theforce required to engage the retention feature 3244 with the frameconnection region 3312 increases and the feeling of attachment for thepatient engaging these components 3244, 3312 becomes more abrupt. Inother words, as the leading surface 3246.1 of the retention feature 3244slides along the lead-in surface 3312.1 of the frame connection region3312 the user may experience a smoother feel of engagement as angle αdecreases. In one example, an angle α of approximately 30 degrees hasbeen found to generate a comfortable feel of attachment for the patient1000. In further examples, angle α may vary from 50 to 70 degrees orfrom 15 to 60 degrees to generate an ideal level of resistance toattachment.

Furthermore, since the feel and force of engagement and disengagement ofthe plenum chamber 3200 and frame connection region 3312 can be tuned orselectively adjusted independently of one another, angles α and β may bechosen to cause the patient to feel a level of resistance to attachmentthat is different from the level of resistance of detachment. In oneexample of the technology, angles α and β may be chosen such that angleβ is greater than angle α, such that the patient feels less resistanceto attachment of the plenum chamber 3200 and frame 3310 than resistanceto detachment. In other words, it may feel harder for the patient todisconnect the plenum chamber 3200 from the frame 3310 than to connectthem.

As can be seen in FIG. 4, one example of the technology includes a pairof retention features 3244, 3245. Also shown in this view, the exemplaryretention features 3244, 3245 are differently sized. Particularly, thisview shows that the retention feature 3245 disposed on an anteriorportion of the plenum connection region 3240 is narrower than theretention feature 3244 disposed on the posterior portion of the plenumconnection region 3240. By sizing the retention features 3244differently, the patient 1000 is only able to attach the plenum chamber3240 to the frame 3310 in one orientation. Such an arrangement is shownin FIG. 10. This avoids patient frustration during attachment, minimisesdamage to the patient interface 3000 that may arise from incorrectattachment, ensures the seal-forming structure 3100 is in the correctorientation to provide a proper seal against the patient's airways andprovide comfort by reducing or avoiding contact with a septum and/or anupper lip of the patient 1000.

In FIG. 10 two frame connection regions 3312, 3313 are shown inengagement with corresponding retention features 3244, 3245. The exampledepicted here shows that the narrower anterior retention feature 3245 issized to correspond to the narrower anterior frame connection region3313. Also, the wider posterior retention feature 3312 is engaged withthe correspondingly sized posterior frame connection region 3244. Anarrangement such as this, where one retention feature is uniquelydimensioned to engage with a corresponding uniquely dimensioned frameconnection region, has the advantage that the patient will only be ableto attach the plenum chamber 3240 to the frame 3310 in one orientation.By limiting the orientations of attachment, the patient 1000 isprevented from assembling the patient interface 3000 improperly andreceiving suboptimal therapy due to an improperly assembled patientinterface 3000. The arrangement described with respect to thisparticular example of the technology is advantageous to the patient 1000that may have difficulty seeing how to correctly engage the componentsdue to vision problems or the patient 1000 who may be assembling thepatient interface 3000 in a dark room, e.g., the bedroom before sleep,because the patient 1000 will only be able to completely assemble thepatient interface 3000 if the components are properly aligned.

As described above, the angles of the leading surface 3246.1 and thetrailing surface 3246.2 on the barb 3246 are important to providing anoptimum amount of resistance to assembly and disassembly of the patientinterface 3000. Also described above is the benefit of sizing respectiveretention features 3244, 3245 and frame connection regions 3312, 3313correspondingly such that a proper orientation of the components isensured upon assembly Properly dimensioning the retention features 3244,3245 and the frame connection regions 3312, 3313 may help to guide theplenum chamber 3200 onto the frame 3310. In other words, the frameconnection regions 3312, 3313 and the retention features 3244, 3245 maybe dimensioned in close conformity to one another such that theperimeter of the frame connection regions and the perimeter of theretention features 3244 to aid in directing and aligning the retentionfeature 3244 into the frame connection region 3312. This may bebeneficial to a patient with limited dexterity due to a disease (e.g.,arthritis) or a patient assembling the patient interface 3000 wherevisibility is diminished whether in a dark bedroom prior to sleep or dueto limited vision. Also, by dimensioning the retention features 3244,3245 and the frame connection regions 3312, 3313 in close conformity toone another this serve to ensure that the seal between the plenumchamber 3200 and the frame 3310 is maintained by facilitating a secureconnection between these two components. Additionally, close conformitybetween the retention features 3244, 3245 and the frame connectionregions 3312, 3313 may serve to facilitate equal alignment of the plenumchamber 3200 on the frame 3310. In one example of the present technologya difference of 0.3 mm to 2 mm may be incorporated between the retentionfeatures 3244, 3245 and the frame connection regions 3312, 3313.

It should also be understood that connection between the frame 3310 andthe plenum chamber 3200 described above and below may be used with othertypes of masks. Such features may be applicable to nasal or full-facemasks as well. Masks that seal under the bridge of the nose, such ascompact nasal masks or compact full-face masks, may also incorporate theconnection features described herein. Furthermore, masks that lack aforehead support may also include these connection features. It is alsoenvisioned that examples of the present technology that include masksthat seal below the tip of the nose, such as those with nasal pillows3130 or a nasal cradle/nasal flange 3101, may also use these connectionfeatures.

Plenum Chamber and Frame Attachment and Removal Sequence

FIGS. 25 to 29 show a sequence of cross-sectional views of theconnection portion 3202 of the plenum chamber 3200 and the frameconnection region 3312 of the frame 3310. These sequential views showthe process of attachment of the plenum chamber 3200 to the frame 3310.While these views show only the attachment of one retention feature 3244to one frame connection region 3312, it should be understood that theremay be more than one retention feature 3244 and more than one frameconnection region 3312, as can be seen in FIG. 10 and discussed above.Therefore, during the attachment sequence of the plenum chamber 3200 andthe frame 3310 there may be more than one instance of the depictedattachment sequence taking place to accomplish complete attachment ofthe plenum chamber 3200 and the frame 3312.

FIG. 25 shows a cross-sectional view of the connection portion 3202 ofthe plenum chamber 3200 and the frame connection region 3312 of theframe 3310 where the connection portion 3202 and the frame connectionregion 3312 are near one another but not in contact. The arrow indicatesthat the connection portion 3202 and the frame connection region 3312are being brought together. It should be understood that for these viewsadditional portions of the plenum chamber 3200 and the frame 3310 havenot been included in the interest of simplicity. Thus, it should also beunderstood that frame connection region 3312 and interfering portion3314 of the frame connection region 3312 are both part of the frame 3310as can be seen, for example, in FIG. 13. Moreover, it should beunderstood then that the frame connection portion 3312 and theinterfering portion 3314 of the frame connection portion 3312 will moverelative to one another through the attachment sequence. Returning toFIG. 25, this view shows that the sealing lip 3250 is not deformed andthe retention feature 3244 is not deformed as neither of thesecomponents 3250, 3244 are in contact with the frame 3310.

FIG. 26 shows the barb 3246 of the retention feature 3244 beginning tomake contact with the frame connection region 3312 of the frame 3310.Specifically, this view shows the leading surface 3246.1 of the barb3246 in contact with the lead-in surface 3312.1 of the frame connectionregion 3312. In this view, the retention feature 3244 and the frameconnection region 3312 are only just coming into contact with oneanother such that the retention feature 3244 is not deflected. Also, thesealing lip 3250 has not been deflected because it is not yet in contactwith the interfering portion 3314 of the frame connection region 3312.As described above, the angle α of the leading surface 3246.1 will beginto affect the resistance the user will feel to engagement of the plenumchamber 3200 and the frame connection region 3312 because the leadingsurface 3246.1 will begin to engage in frictional contact with thelead-in surface 3312.1.

FIG. 27 shows the plenum chamber 3200 and the frame 3310 further alongin the attachment sequence such that the retention feature 3244 isdeflected by contact with the frame connection region 3312. As can beseen in this view, the frame connection region 3312 and the interferingportion 3314 of the frame connection region 3312 are nearer to theconnection portion 3202. Also shown in this view, the leading surface3246.1 of the barb 3246 is in contact with a portion of the lead-insurface 3312.1 that is closer to the retaining surface 3312.2. In otherwords, the barb 3246 can be seen having moved closer to attachment withthe frame connection region 3312 and having moved relative to theposition shown in FIG. 26. As described earlier, the connection portion3202 and the plenum connection region 3240 of the plenum chamber 3200may also be deflected from a pinching force generated by the patient1000. FIG. 27 also indicates that the retention feature 3244 has beendeflected by contact with the frame connection region 3312 and thedashed lines show the outline of the retention feature 3244 in anundeformed state. FIG. 27 also shows that the sealing lip 3250 is notyet in contact with the interfering portion 3314 of the frame connectionregion 3312, and, therefore, the sealing lip 3250 is not deformed.Although, not shown in this view it should also be understood that theframe connection region 3312 may deflect away from the retention feature3244 due to the force of these parts 3312, 3244 being forced together.

In FIG. 28 the plenum chamber 3200 and the frame 3310 are nearlyattached and the retention feature 3244 is nearly completely engagedwith the frame connection region 3312. In this view the retentionfeature 3244 is still deformed but the barb 3246 is in contact with adifferent portion of the frame connection region 3312. Specifically, thetrailing surface 3246.2 of the barb 3246 is now in contact with theretaining surface 3312.2 of the frame connection region 3312. Also, dueto the fact that the angle at which the trailing surface 3246.2 and theretaining surface 3312.2 contact one another, the retention feature 3244and the frame connection region 3312 may be urged into engagement by theinherent tendency of the deflected retention feature 3244 to return toits undeformed state, in effect drawing these parts together after acertain insertion distance is reached. FIG. 28 also shows the outline ofthe retention feature 3244 in an undeformed state with dashed lines.Also in this view it can be seen that the sealing lip 3250 is in contactwith the interfering portion 3314 of the frame connection region 3312.At this point in the attachment sequence a seal may begin to be formedby the contact of the sealing lip 3250 and the interfering portion 3314of the frame connection region 3312. The sealing lip 3250 may also beslightly deflected by contact against the interfering portion 3314 ofthe frame connection region 3312.

FIG. 29 shows the plenum chamber 3200 and the frame 3310 fully attachedby engagement of the barb 3246 of the retention feature 3244 with theframe connection region 3312. In this view the retaining surface 3312.2may be relatively flush against the trailing surface 3246.2. Theretention feature 3244 may also no longer be deflected by contact withthe frame connection region 3312. The retention feature's 3244 return toan undeformed state from its deflected or deformed state, as shown inFIG. 28, may generate an audible click as the barb 3246 and theretention feature 3244 move to the position shown in FIG. 29 from theposition shown in FIG. 28. This re-assuring audible click may beadvantageous in that it provides the patient 1000 with feedback that theplenum chamber 3200 and the frame 3310 are fully engaged. By providingthe patient 1000 with this feedback upon completion of engagement thepatient 1000 may be able to use the patient interface 3000 withconfidence that the plenum chamber 3200 and the frame 3310 are securelyattached and will not separate while the patient 1000 is asleep andreceiving therapy.

Furthermore, a desired level of sealing contact may be achieved when theplenum chamber 3200 and the frame 3310 are attached as shown in FIG. 29.The sealing lip 3250 can be seen deflected against the interferingportion 3314 of the frame connection region 3312. By being deflected asshown, the sealing lip 3250 may be urging itself against the interferingportion 3314 of the frame connection region 3312 with sufficient forcedue to the tendency of the sealing lip 3250 to return to its undeformedstate such that a desired seal is generated between these components.Furthermore, as air pressure within the plenum chamber 3200 increaseswhen therapy is applied, the sealing lip 3250 is forced to deflecttowards the portion 3314 of the frame connection region 3312 therebyincreasing the sealing force in this area. Even though a compressionseal is formed between the retaining structure 3242 and frame connectionregion 3312 when the plenum chamber 3200 is engaged with the frame 3310,a pressure-activated seal also is formed between sealing lip 3250 andthe portion 3314 of the frame connection region 3312 on engagement whichstrengthens as air pressure within increases. It may be possible incertain examples that the compression seal is not air tight resulting inundesired leakage.

Also, if a very large amount of compression of components is required toform the compression seal, this may hinder easy attachment anddetachment of the plenum chamber 3200 to the frame 3310 possiblyrequiring more than a single hand to perform the operation or asignificant amount of effort. Therefore, in one example of the presenttechnology, the compression seal functions predominantly for the purposeof retention rather than of seal, and the pressure-activated sealfunctions predominantly for the purpose of creating and maintaining anair tight seal. It should be understood that such a sealing effect maybe occurring about the periphery of the junction between the plenumchamber 3200 and the frame 3310. For example, FIG. 17 shows the sealinglip 3250 in a similarly deflected state against the frame connectionregion 3312 at a region separate from the retention features 3244.Moreover, it can be seen in FIG. 5, for example, that the sealing lip3250 extends around the perimeter of the plenum chamber 3200. Byextending the sealing lip 3250 inwardly around the perimeter of thejunction between the plenum chamber 3200 and the frame 3310 the desiredlevel of sealing can be achieved throughout this region, therebypreventing undesired leakage of pressurized gas.

Additionally, it should be understood that the sealing lip 3250 may bepressing against the interfering portion 3314 of the frame connection3312 with a force that is urging these parts to separate. However, thefriction force due to structural engagement of the trailing surface3246.2 of the barb 3246 with the retaining surface 3312.2 of the frameconnection region 3312 should be sufficient to resist the force of thesealing lip's 3250 tendency to return to an undeformed state andseparate the plenum chamber 3200 from the frame 3310.

As for removal of the plenum chamber 3200 and the frame 3310, it shouldbe understood that this process is substantially the reverse order ofthe process described above. In other words, the user may separate theplenum chamber 3200 from the frame 3310 by pulling these components inopposite directions and the view of FIG. 29 may be the beginning of theseparation process and FIG. 25 may represent the view wherein the plenumchamber 3200 and the frame 3310 are fully separated. Pinching of theplenum chamber 3200 proximal to the plenum connection region 3240 orpinching the plenum connection region 3240 and pulling away from theframe 3310 may assist in removal of the plenum chamber 3200 from theframe 3310. It is also envisaged that the patient 1000 may pinch theplenum chamber 3200 for the purpose of gripping it, at any location, forexample, the nasal pillows 3130 or stalks 3150 and simply pull it awayfrom the frame 3310. A twisting motion while pulling may also assist indisengaging the plenum chamber 3200 from the frame 3310.

Hard-to-Hard Connection

The plenum connection region 3240 and the frame 3310 may be assembledand attached as shown in FIGS. 25 to 29. As stated above, the plenumconnection region 3240 and/or retaining structure 3242 may be comprisedof a semi-rigid material, e.g., high durometer silicone (a higherdurometer than plenum chamber 3200)/TPE, plastic, nylon, polypropylene,polyamide and/or polycarbonate. The plenum connection region 3240 can beconstructed in the form of a continuous ring or oval, two C-shapedclips, one C-shaped clip, or a single continuous piece but onlysurrounding a part of the plenum chamber 3200. The clip may function asa spring clip and be in the form of a C-section or double C-section. Thespring force of the spring clip may be provided by resiliency of theplenum connection region 3240 being stretched against the frameconnection regions 3312, 3313 or interfering portion 3314 of the frame3310. In another example, a clip form may be not be necessary and onlythe retention features 3242, 3244 are permanently and directly connectedto the plenum chamber 3200 without a plenum connection region 3240and/or retaining structure 3242 for engagement with the connectionregions 3312, 3313. It is also envisioned that one example of thepresent technology may also include the frame 3310 being comprised ofthe same or a similar semi-rigid material as the plenum connectionregion 3240. By manufacturing the frame 3310 and the plenum connectionregion 3240 of semi-rigid material, a “hard-to-hard” connection orbonding interface may be created. This “hard-to-hard” connection, inconjunction with the structural features of the plenum connection region3240 and the frame connection region 3312, may provide the patient 1000with a confident feeling (e.g., by providing an audible snap fit orre-assuring click sound) of the connection between the plenum chamber3200 and the frame 3310 when assembling the patient interface 3000.Since a secure fit between the plenum chamber 3200 and the frame 3310 ishelpful to ensure that the patient 1000 receives optimal therapy throughthe patient interface 3000, a design that provides the patient 1000 withconfidence that a secure fit has been achieved is beneficial. Ahard-to-hard connection as described herein may also be beneficial inthat it may add stability to the seal made by the seal-forming structure3100. This is contrast to a hard-to-soft or a soft-to-soft connectionwhere either or both the plenum chamber and frame are made of a floppymaterial which makes it difficult for arthritic hands to properly engagethe plenum chamber and frame easily, especially in darkened room.

Although the retention features 3242, 3244 are described as provided onthe plenum chamber 3200 and the connection regions 3312, 3313 areprovided on the frame 3310, it may be possible to switch the location tothe retention features on the frame and the connection regions on theplenum chamber. Also, there may be a combination of a retention featureand a connection region on one part that corresponds with a connectionregion and a retention feature on the other part.

Method of Making the Plenum Chamber

A process to manufacture plenum chamber 3200 may comprise the step ofmoulding plenum connection region 3240 in a first tool, removing mouldedplenum connection region 3240 from the first tool, inserting the plenumconnection region 3240 into a second tool, and moulding a portion ofplenum chamber 3200 comprising connection portion 3202 in the secondtool. Plenum connection region 3240 may be chemically bonded and/ormechanically interlocked to connection portion 3202.

In one form, the sealing lip 3250 is constructed and arranged tointerfere with the interfering portion 3314 (FIG. 13) of frameconnection region 3312 when plenum chamber 3200 and frame 3310 areassembled together. In use, sealing lip 3250 is caused to resilientlyflex away from a resting position (FIG. 6) when assembled with theinterfering portion 3314 of frame connection region 3213, and at leastin part as a result of being a resilient material, pushes against theinterfering portion 3314 (FIG. 12) to resist or prevent leakage of airbetween sealing lip 3250 and the interfering portion 3314. Although thesealing lip 3250 has been described as provided with the plenum chamber3200, the sealing lip may be provided on the frame 3310. Although onesealing lip has been described, it is possible two or more sealing lipsmay be provided, with at least one with the plenum chamber 3200 and atleast one with the frame 3310.

Positioning and Stabilising Structure 3300

Note that in one form of the present technology, a number of structuralfeatures form part of a positioning and stabilising structure 3300,e.g., a headgear assembly (which may be referred to simply as headgear).In an alternative form of the present technology, one or more of thosefeatures are located on the frame 3310. For example, a flexing joint3305 may be wholly or partly located on the headgear, or on the frame3310. Also, the extension 3350 may perform the same function as theflexing joint 3305 except that it is integrally formed with therigidiser arm 3302.

The seal-forming structure 3100 of the patient interface 3000 of thepresent technology may be held in sealing position in use by thepositioning and stabilising structure 3300 (FIGS. 75, 76 and 166). Inone form, the positioning and stabilising structure 3300 comprisesheadgear. It should be appreciated that the positioning and stabilisingstructure 3300 may, in one form of the technology, be referred to asheadgear.

Headgear may be removably connectable to a portion of the patientinterface such as the positioning and stabilising structure 3300 via aheadgear connector.

Straps

The positioning and stabilising structure 3300 may comprise at least onestrap 3301 (see, e.g., FIG. 65) and at least one rigidiser arm 3302(see, e.g., FIG. 67). The strap 3301 may be made of an elastic materialand may have elastic properties. In other words, the strap 3301 may beelastically stretched, e.g., by a stretching force applied by thepatient and, upon release of the stretching force, returns or contractsto its original length in a neutral state. The strap 3301 may be made ofor comprise any elastomeric material such as elastane, TPE, siliconeetc. The material of the strap 3301 may also represent a combination ofany of the above materials with other materials. The strap 3301 may be asingle layer or multilayer strap. The strap 3301, particularly the sidestrap portions 3315, 3316 in contact with the patient 1000 during use,may be woven, knitted, braided, molded, extruded or otherwise formed.The strap 3301 may comprise or may be made of a textile material such asa woven material. Such material may comprise artificial or naturalfibers for, on the one hand, providing desired and beneficial surfaceproperties such as tactile properties and skin comfort. On the otherhand, the material of the strap 3301 may include elastomeric materialfor providing the desired elastomeric properties. The entire strap 3301,including the side strap portions 3315, 3316 and back strap portion3317, may all be stretchable. This enables the entire length of thestrap 3301 to be stretched which leads to a comfortable forcedisplacement profile. In order for the strap 3301 to be stretched inuse, the length of the strap 3301 may be less than the average smallhead circumference of patients. For example, the length of the strap3301 may be less than 590 mm in one example and less than 500 mm inanother example. However, straps 3301 of different lengths may beprovided to patients depending on their head circumference which may begender specific. For example, a small sized strap may be 490 mm inlength and a large sized strap may be 540 mm. In some circumstances thismeans that the length of the strap 3301 need not be stretched by a largedistance (i.e. small sized strap for a large head circumference) whichwould have unnecessarily high headgear tension for such patients andalso a less smooth force displacement profile as the small sized strap3301 is being stretched to longer lengths.

The strap 3301 is rigidised at a certain sections, for example, from theframe 3301 up to a position proximal to the patient's cheekbone by theinserted rigidiser arms 3302. The strap 3301 may take the form of ahollow ribbon. The strap 3301 may be considered to be threaded over therigidiser arm 3302 when it is slipped onto the rigidiser arm 3302 andsecured at one end of the rigidiser arm 3302 proximal to the frame 3301.

In one example, the strap 3301 including the side strap portions 3315,3316 and back strap portion 3317 are made by warp knitting a textilematerial. The strap 3301 is a 3D knitted fabric that is knit by computercontrol as a single unitary piece. Variation in the thread and stitchingmay occur at various positions along the strap 3301 to adjust theelasticity and strength and durability of the strap 3301 at certainlocations. For example, at the locations of the openings, insertionpoints or button-holes 3303, 3304 and the bifurcation point 3324 for theback strap portions 3317 a, 3317 b, an additional thread may be knittedto provide reinforcement of the strap 3301 to prevent failure/breakageof the strap 3301 at these locations that subject to high stress whenthe strap 3301 is stretched during repeated and prolonged use. Both theknitting method (i.e. warp knitting) and the elastic textile material(e.g. elastane) of the strap 3301 contribute to the elastic recovery ofthe strap 3301 after washing the strap 3301 in water and dried. In otherwords, the elasticity of the strap 3301 can be maintained afterprolonged use by periodically washing the strap 3301 and therefore itsoperational life is extended.

In FIGS. 65 to 73, the strap 3301 is shown as being a single continuousstrap with two pocketed ends 3311, 3313 for being attached, directly orvia a flexible joint 3305, to a frame 3310. However, it may beappreciated that the strap 3301 may comprise multiple individual strapswhich are or may be directly connected to one another, for example,stitching or ultrasonic welding. In FIG. 65, the strap 3301 andpositioning and stabilising structure 3300 is shown without anyadjustment or variation means. Such adjustment may be provided, however,by varying where the strap 3301 is secured to a patient interface 3000or other connection elements more rigid than the strap 3301 such as aflexible joint 3305. Turning to FIG. 72, in addition or alternatively,adjustment could be allowed by adding a mechanism, such as slide overladder lock clips 3305.1 on the back 3317 or side strap portions 3315,3316 (as shown, e.g., in FIGS. 71 to 73) or by otherwise adjusting theelastic length of the strap 3301 and positioning and stabilisingstructure 3300, respectively. In the example shown in FIG. 65, the strap3301 has a tube-like configuration as can be taken from the respectiveschematic views in FIGS. 68 to 70 indicating an oval or circular shapeor respective marks 3321 a-d, 3323 a-e of circular or oval shapeindicating the (visible) outer surface facing towards the viewer assolid and the (invisible) inner wall facing away from the viewer indashed lines, as well as by the cross-sectional view according to FIG.66. However, it will be appreciated that the positioning and stabilisingstructure 3300 may take any other shape such as flat or sheet-likeshape, single, multi-layer or laminate construction. The strap 3301 mayhave a longitudinal axis which may be understood to be the axissubstantially parallel to the paper plane, along which the strap 3301extends (see, e.g., dashed line in FIG. 65).

The strap 3301 have may reinforced stitching to improve durability andminimise or prevent failure points. For example, the areas of the strap3301 at the button-holes 3303, 3304 and also at the location where itbifurcates into two back strap portions 3317 a, 3317 b, at bifurcationpoints 3324, are subject to high stress when stretched. The tendency ofthe material is to split away from each other at a split region 3326 andtherefore reinforced stitching at these areas is one way to address thisconcern. In an example, a central seam runs along the centrelongitudinal axis of the strap 3301 and functions as reinforcedstitching. Also, the distal edges of the strap 3301 and the opening atthe button-holes 3303, 3304 may be ultrasonically welded to fuse anystray fibers and strengthen the strap 3301 in these regions.Advantageously, this also prevents fraying of the fibers of the strap3301 after extended use and repeated washing. Other techniques areenvisaged for reinforcing and strengthening the pocketed end 3311,distal edges and button-hole 3303, which may include additional materialsuch as tape. The tape may include branding and logo information also.

FIGS. 123 to 125 show increasingly detailed views of the split region3326 between the upper back strap portion 3317 a and the lower backstrap portion 3317 b. The edges of the upper back strap portion 3317 aand the lower back strap portion 3317 b should be understood to not beperfectly smooth as a result of the knitting process and it should befurther understood that these views show the edges with a great deal ofmagnification such that imperfections are visible. With the naked eyethe undulations on the edges of the upper back strap portion 3317 a andthe lower back strap portion 3317 b would not be so easily visible andare not generally discernible by the patient 1000 by touch.Additionally, stippling is used in these views to show the texture ofthe back strap portions 3317 a, 3317 b while the split region 3326 isshown blank because the split region 3326 is an absence of material.

FIGS. 126 to 131 show various detailed views of the bifurcation point3324 that exists where the upper back strap portion 3317 a and the lowerback strap portion 3317 b split off from a side strap portion 3315,3316. Also visible in these views is a reinforced portion 3325 that mayinclude additional stitching or welding at or proximal to thebifurcation point 3324. The reinforced portion 3325 may aid inpreventing the side strap portions 3315, 3316 from splitting and/ortearing due to stress from the repeated separation of the upper backstrap portion 3317 a and the lower back strap portion 3317 b. In otherwords, the reinforced portion 3325 may provide additional strength at alocation of stress concentration near the bifurcation point 3324. Alsoshown in these views are the upper back strap portion 3317 a and thelower back strap portion 3317 b at various angles of separation θ. Theseviews may be understood to show that the reinforced portion 3325provides additional strength at the bifurcation point 3324 when theupper back strap portion 3317 a and the lower back strap portion 3317 bare spread from one another at large angles θ.

Referring to FIGS. 176 to 181, in one example of the present technology,the ends of the strap 3301 have a reinforcement portion 3327 with amaterial folded over the end of the strap 3301. This provides furtherreinforcement in this area in addition to the welded ends 3311.1, 3313.3(see FIG. 81). The material of the reinforcement portion 3327 may be adifferent material to the strap 3301. The reinforcement portion 3327 mayavoid or mitigate the likelihood of a patient 1000 tearing or rippingthe strap 3301 along its longitudinal axis beginning from this area. Thereinforcement portion 3327 helps provide a visual and tactile indicationto the patient 1000 on how to slip on or remove the strap 3301 from therigidiser arm 3302 because it may assist in identifying the location ofthe button-hole 3303, 3304. The corners 3328 of the reinforcementportion 3327 have been cut and are rounded so that the corners 3328approximately match the rounded corners of the rigidiser arm 3302 at itsdistal free ends 3302.1 (see FIGS. 50, 52, 55, 57, 58, 60). Thisprovides a snug fit with the rigidiser arm 3302 which is moreaesthetically pleasing. The rounded corners 3328 provides a soft edge toavoid facial scratching that could occur if they were sharp cornersinstead.

Rigidiser Arms

FIG. 67 shows an example of a rigidiser arm 3302. As shown, therigidiser arm 3302 may take a crescent or semi-circular shape. Therigidiser arm 3302 may have a generally elongate and flat configuration.In other words, the rigidiser arm 3302 is far longer and wider(direction from top to bottom in the paper plane) than thick (directioninto the paper plane). The rigidiser arm 3302 has a three-dimensionalshape which has curvature in all three axes (X, Y and Z). Although thethickness of the rigidiser arm 3302 may be substantially uniform, itsheight varies throughout its length. The purpose of the shape anddimension of the rigidiser arm 3302 is to conform closely to the cheeksof the patient in order to remain unobtrusive and frame the patient'sface and cheeks. The ends 3319 a, 3319 b of rigidiser arm 3302 may berounded and/or slightly angled relative to the remainder of therigidiser arm 3302. While the rigidiser arm 3302 may be flat, asindicated by the paper plane in FIG. 67, it will be appreciated, thatthe rigidiser arm 3302 may have a desired spatial configuration also inthe direction into the paper plane in FIG. 67, particularly in order toallow improved alignment with the shape of a patient's face, such as theshape of a patient's cheek or head side region (see, e.g., FIGS. 71 and72). The rigidiser arm 3302 may have a longitudinal axis which may beunderstood to be the axis substantially parallel to the paper plane,along which the rigidiser arm 3302 extends (see dashed line in FIG. 67).

The rigidiser arm 3302 is more rigid than the strap 3301 and less rigidthan the mask frame 3310. In particular, the rigidiser arm 3302 and/orthe strap 3301 are such that in combination the rigidiser arm 3302imparts a shape, and an increased degree of rigidity in at least onedirection or in or around at least one axis, to the strap 3301. Also,the rigidiser arm 3302 guides or defines the direction or path ofstretch for the strap 3301. In other words, the patient stretches thestrap 3301 in a direction substantially parallel to the longitudinalaxis of the rigidiser arm 3302. Stretching of the strap 3301 in otherdirections leads to rotation of the rigidiser arm 3302 relative to themask frame 3310 which is undesirable. The rigidity of the rigidiser arm3302 biases the rigidiser arm 3302 towards its natural, unrotated,untwisted and undeformed state. To some degree, this enables thepositioning and stabilising structure 3300 to be self-adjustingheadgear. The self-adjusting function avoids manually shortening orlengthening the material length of headgear straps and then rememberingthe adjusted length. This has typically been a cumbersome processbecause headgear straps on both sides of the face have to be shortenedor lengthened one at a time. It may remove the ability for patients toover tighten the headgear when such high levels of headgear tension isnot required to maintain a good sealing force. In the shown example,strap 3301 has a tube- or sleeve-like configuration. In other words, thestrap 3301 is hollow in order to receive the insertion of the rigidiserarm 3302 which is slid into the strap 3301 via the button-hole 3303. Inanother example, the rigidiser arm 3302 may be permanently connected tothe strap 3301 at least in one location, for example, at the anchorpoint it is overmolded or glued to form an integral chemical bond(molecular adhesion) between the rigidiser arm 3302 and the strap 3301.

Strap 3301 comprises side strap portions 3315, 3316 and a back strapportion 3317 located between the side strap portions 3315, 3316. Sidestrap portions 3315, 3316 are adapted to extend along the sides of apatient's head when being worn while back strap portion 3317 is adaptedto extend along the back of a patient's head, as shown in FIGS. 4 to 8and 166. Back strap portion 3317 may be comprised of two, three or morestraps arranged in parallel, particularly for providing stability.Although the smaller back strap portions 3317 a, 3317 b have beenillustrated as equal in length, it is envisaged that one back strapportion is longer than the other back strap portion. The greater thenumber of smaller back strap portions 3317 a, 3317 b for the back strapportion 3317, the greater the spring effect provided. In other words, asthe number of same sized smaller back strap portions 3317 a, 3317 bincreases when the strap 3301 is manufactured, the more tension isexerted on the side strap portions 3315, 3316 to be pulled closer toeach other by the back strap portions 3317 a, 3317 b. In the shownexample, side strap portions 3315, 3316 of strap 3301 bifurcate into twoback strap portions 3317 a, 3317 b. In one example, each back strapportion 3317 a, 3317 b has half the amount of elastane material comparedto each side strap portion 3315, 3316 of the strap 3301. In one example,the positioning and stabilising structure 3300 is connected to the maskframe 3310 by a removable connection between strap 3301 and therigidiser arm 3302 via a button-hole 3303, 3304 and the rigidiser arm3302 being permanently connected to the mask frame 3310 via mechanicalinterlock. In another example, a flexible joint 3305 made from TPE maypermanently connect to the rigidiser arm 3302 and the mask frame 3310.The flexible joint 3305 is overmolded with the mask frame 3310 forpermanent connection and the flexible joint 3305 is permanentlyconnected to the rigidiser arm 3302 via mechanical interlock. In anotherexample, the flexible joint 3305 may be made from the same material asthe rigidiser arm 3302, for example, Hytrel®, and is integral with therigidiser arm 3302 and the flexible joint 3305 is permanently connectedto the mask frame 3310 via mechanical interlock. The strap 3301 isremovably connected with the rigidiser arm 3302 via a button-hole 3303,3304.

The engagement of the strap 3301 to the rigidiser arm 3302 may occur inone location proximal to the mask frame 3310. This type of engagementallows for a maximum range of motion i.e. stretching of the strap 3301.This engagement is removable to enable the strap 3301 to be fullydetachable from the rigidiser arm 3302 and in turn, the mask frame 3310to facilitate washing of the strap 3301. The engagement functions as ananchor point for the strap 3301 such that when the strap 3301 isstretched, the stretching force is directed outwardly away from theanchor point. Turning to FIGS. 48 to 60, the end of the strap 3301 atthe anchor point is retained by at least the distal edge of therigidiser arm 3302 and/or a protruding end 3306 extending from therigidiser arm 3302.

It will be appreciated by the skilled person that the rigidiser arm 3302as referred to herein may be more rigid than the strap 3301 and allowsthe rigidiser arm to impart a shape to the strap 3301. The rigidiser arm3302 may be more rigid in or around at least one axis and isinextensible in contrast to the strap 3301 which can be stretched alongat least one axis. In another example, the rigidiser arm 3302 isextensible/stretchable in a direction substantially parallel to itslongitudinal axis. Although elastomers typically can stretch, somethermoplastic polyester elastomers do not stretch but are flexible, forexample, Hytrel® 5556 manufactured by DuPont®. For example, therigidiser arm 3302 may have a scissor linkage structure or telescopicstructure which enables the rigidiser arm 3302 to move between acompressed position to a fully elongated position. An extensiblerigidiser arm 3302 may allow a better fit for patients 1000 who havelonger faces so that the length of the rigidiser arm 3302 can beadjusted appropriately. Alternatively, the rigidiser arm 3302 may bereferred to as a yoke and/or a stiffener. A yoke may be understood to bea rigid element adapted to support the straps 3301 of the positioningand stabilising structure 3300. A rigidiser arm 3302 may be understoodto be a rigid element shaping the straps 3302 of the positioning andstabilising structure 3300 when worn on the face.

Attachment of Straps and Rigidiser Arms

The side strap portions 3315, 3316 of strap 3301 shown in FIG. 65 eachinclude two button-holes 3303, 3304. The button-holes 3303, 3304 may belocated at the outer surface of strap 3301, i.e., the surface facingaway from the patient 1000 when being worn, and are adapted to receiverigidiser arm 3302 in order to insert the rigidiser arm 3302 into theinterior of the tube- or sleeve-like strap 3301 or to remove ittherefrom. Alternatively, the button-holes 3303, 3304 may be located atthe inner surface of the strap 3301. The button-holes 3303, 3304 may beoriented and/or shaped such that the rigidiser arm 3302 may be insertedand/or removed through such button-hole 3303 in order to assemble thepositioning and stabilising structure 3300 while still preventingaccidental removal or separation of the rigidiser arm 3302 from thestrap 3301 during use. As shown in FIG. 65, this may be achieved byproviding button-holes 3303 having a slit-like configuration, e.g.,similar to button-holes, which may be oriented alongside or transverselyto the strap 3301. Alternatively, the button-holes 3303 may be orientedacross the strap 3301 if required. In other words, the elongateextension of the button-hole 3303, 3304 may extend substantially coaxialto the longitudinal axis of both strap 3301 and rigidiser arm 3302. Thisallows, particularly due to the elasticity of strap 3301, an easyinsertion of the rigidiser arm 3302 into the tube- or sleeve-like strapor part of strap 3301 while, at the same time, preventing its accidentalremoval. An end portion of the strap 3301 between the distal tip of thestrap 3301 and the button-hole 3303 wraps over the edge of the rigidiserarm 3302 and functions an anchor point. This edge of the rigidiser arm3302 or anchor point may be a catching member. This end portion of thestrap 3301 may also be referred to as the pocketed end 3311. Thisprevents the strap 3301 from slipping off the inserted rigidiser arm3302 when the strap 3301 is stretched and adjusted while donning ordoffing the patient interface 3000.

Referring to FIGS. 185 and 186, the rigidiser arm 3302 may be insertedinto the first button-hole 3303 of the strap 3301. Said another way, thestrap 3301 may be slipped over the rigidiser arm 3302 via thebutton-hole 3303. The distal free end 3302.1 of the rigidiser arm 3302is first inserted into the strap 3301 via the button-hole 3303. Therigidiser arm 3302 is pushed further inside the strap 3301 until most orsubstantially the entire rigidiser arm 3302 is inserted into the strap3301 such that the end portion of the strap 3301 can securely anchor tothe edge of the rigidiser arm 3302. Some material of the strap 3301 nearthe button-hole 3303 is adjusted to sit beneath the outer side 3319 ofthe protrusion 3309 (see FIG. 38). Once inserted in the strap 3301, therigidiser arm 3302 may be left floating generally unrestricted insidethe strap 3301, as can be seen in FIGS. 6 to 8. Most importantly, thebutton-hole 3303 should be above the attachment point because the endportion of the strap 3301 is caught against the protruding end 3306 ofthe rigidiser arm 3302 to secure the strap 3301 to the rigidiser arm3302 and also pulls against the protruding end 3306 when the strap 3301is stretched. Typically, the position of the attachment point betweenthe rigidiser arm 3302 and strap 3301 is more important than the type ofattachment, for example, using a button-hole 3303, 3304 in the strap3301. Referring to FIGS. 182 to 184, the type of attachment between therigidiser arm 3302 and strap 3301 may facilitate easy removal of thestrap 3301 from the rigidiser arm 3302 to enable separate washing of thestrap 3301. In other words, the washing and cleaning regime for thestrap 3301 may be at different times from the mask frame 3310. Thepatient 1000 slightly stretches the strap 3301 around the button-hole3303 to unfasten the strap 3301 from the rigidiser arm 3302. After thedistal end of the strap 3301 is unfastened, the strap 3301 may be pulledoff completely from the rigidiser arm 3302 via the button-hole 3303.

In addition or alternatively, the rigidiser arm 3302 is affixed to thestrap 3301. The affixing may be effected by attaching or affixing thesecond end of the rigidiser arm 3302, which after the insertion is nearthe button-hole 3303, to the strap 3301 of the positioning andstabilising structure 3300. The fixation may be localized, as discussedin the introductory portion of the description. Here, the connectionbetween the rigidiser arm 3302 and the strap 3301 is not distributedalong the length of the strap 3301, but is localized in the areaadjacent to the button-hole 3303. Alternatively, such connection may beestablished in the area adjacent to the button-hole 3304. The affixingmay be performed by way of sewing, welding, gluing, heat staking,clamping, buttoning, snapping a cover over the end or snapping on anexternal part by pushing the rigidiser arm 3302 inside the strap 3301and fixing both the strap and the rigidiser arm 3302 to an externalcomponent, such as an external clip that holds both the strap and therespective end of the rigidiser arm 3302. The strap 3301 mayalternatively be chemically bonded to the rigidiser arms 3302. The clipmay also be used to attach the end of the strap 3301 to a respective endof a mask frame 3310. As such, the clip may be a part of the mask frame3310 itself.

With the present technology, while the strap 3301 is arranged to takethe shape of the rigidiser arm 3302, it is still able to stretchsubstantially along its entire length. Thus, the rigidiser arm 3302imparts the required shape which directs the pressure of the positioningand stabilising structure 3300 to the required portions of the face,while the elastic positioning and stabilising structure 3300 maintainsits entire operational length and is able to freely stretch over therigidiser arm 3302. Additionally, the rigidiser arms 3302 may decoupletube torque in the coronal plane. Also, in particular, the sharp bend3307 of the rigidiser arms 3302 may serve to handle and decouple anytube torque in the sagittal plane. At the same time, the strap 3301 ofthe positioning and stabilising structure 3300 may cover the rigidiserarm 3302 and provides a soft feel and enhanced comfort.

The sharp bend 3307 provides stability for the patient interface 3000.If the patient 1000 is sleeping on their side, the rigidiser arm 3302against the side of the face on the bedding is pushed inwardly. Thesharp bend 3307 decouples this movement in the coronal plane to preventdisruption of the seal force. The sharp bend 3307 has a tighter turn onits upper surface (facing away from the patient's face) compared to itslower surface (facing the patient's face). The lower surface of thesharp bend 3307 has a larger radius (washed out) than the upper surfaceof the sharp bend 3307 which smooths it out and avoids or minimisesfacial marking on the patient 1000 since the contact pressure is lessconcentrated if there is any contact on the patient's septum and/orupper lip (from nose droop caused by tube weight or tube torque). Thedistance between the two sharp bends 3307 is about 50 mm

Although being shown and discussed with regard to the specific examplesshown in FIGS. 65 to 70, it will be appreciated that strap 3301, or eachof the strap side strap portions 3315, 3316 may be provided with onebutton-hole 3303, 3304 only. However, two or more button-holes may beprovided. Alternatively or in addition, the strap 3301 may not betube-like or sleeve-like but may have a flat single or laminate layerconfiguration. Here, the rigidiser arm 3302 may be positioned relativeto the strap 3301 by the provision of retaining means including one ormore loops, sleeve-like portions or pockets provided at the outersurface (e.g., the surface facing away from the patient in use) of strap3301.

In addition or alternatively, combinations of the different connectionmechanisms described herein may be provided. For example, rigidiser arm3302 may be fixed to the strap 3301 at a single point or localized area,as discussed above, adjacent, e.g. pocketed ends 3311, 3313 of strap3301 while being held next to strap 3301 by provision of a loop orsleeve-like element provided at the outer surface of strap 3301, e.g.,in the area of the marks 3321 b, 3323 b. In other words, the rigidiserarm 3302 may be connected to the strap 3301 by fixing it at onelocalized point or area only, while functioning as an additional guidingelement to strap 3301. Such guiding element functionality may beprovided by a loop- or sheath-like portion or passage or a pocket of thestrap 3301 into which or through which rigidiser arm 3302 extends basedon the shape of the strap 3301 shown in FIG. 66. The strap 3301 may betubular, but not necessarily cylindrical. This allows the longeststretch path possible for the strap 3301. Alternatively, the rigidiserarm 3302 may be disposed unattached into one or more pockets (e.g., asingle open-ended pocket of sheath of appreciable length supporting therigidiser arm somewhere in the middle, or a pair of pockets, eachsupporting a respective end of the rigidiser arm), or a plurality ofloops distributed along the length of the strap 3301. Such guidingelement functionality, whether attached at one end or not, allowssubstantially free movement or floating of the rigidiser arm 3302relative to the strap 3301. Such configuration would allow the sameadvantages and benefits as the configuration discussed above.Additionally, according to an example of the technology, the rigidiserarms 3302 do not stretch or flex in the same direction as the strap3301. Rather, the rigidiser arm 3302 may stretch or flex in a planesubstantially perpendicular to its longitudinal axis.

In the shown and discussed examples, rigidiser arm 3302 does not extendbeyond the end(s) of strap 3301. However, according to alternativeaspects, the rigidiser arm 3302 may be, e.g., fixed to strap 3301 at apoint or area adjacent to the respective pocketed ends 3311, 3313 whileextending beyond strap 3301. In such a configuration, rigidiser arm 3302may impart a shape, geometry, and/or rigidity to the strap 3301 and atthe same time, provide structural means such, as a flexible joint 3305,for connecting with a patient interface 3000. This allows rigidiser arm3302 to function both as rigidiser arm 3302 as well as a connector forconnecting the strap 3301 and the positioning and stabilising structure3300, respectively, to the frame 3100, plenum chamber 3200, orseal-forming structure 3100.

FIGS. 113 to 122 shows detailed views of the connection between thepocketed ends 3311, 3313 and the rigidiser arms 3302. FIGS. 113 and 114show the pocketed ends 3311, 3313 around respective protruding ends 3306of the rigidiser arms 3302. The protruding ends 3306 are not visible inthese views because they are covered by the pocketed ends 3311, 3313. Astraight section 3351 on an extension 3350 (discussed further below) ofthe rigidiser arm 3302 is shown with indicia 3358 on an outer surface3355 of the extension 3350. The indicia 3358 may be pad printed, araised surface or an embossment to help the patient 1000 orient thedevice 3000 during use when in a darkened environment. The straightsection 3351 of the extension 3350 may be seen extending outwardly fromthe button-hole 3303 of the respective pocketed end 3311, 3313. Thestraight section 3351 is a part of the rigidiser arm 3302, as shown inFIGS. 47 to 60, and the rigidiser arm 3302 facilitates the connectionbetween the strap 3301 and the mask frame 3310. FIG. 114 shows a similarview to FIG. 113, however the outer surface 3355 of the straight section3351 is without indicia. It should be understood that FIG. 113 depictsthe connection between one rigidiser arm 3302 and the respectivepocketed end 3311 while FIG. 114 depicts the connection between anotherrigidiser arm 3302 and the other respective pocketed end 3313. Byplacing indicia 3358 on only one outer surface 3355, the patient 1000can use the sense of touch to determine the orientation of the device3000 to aid in fitting in a darkened environment. FIG. 114 also shows aflange 3359 that is visible through the button-hole 3303.

FIG. 115 shows similar features to FIG. 114 but is a more detailed viewto better show the relationship between the flange 3359 and the pocketedend 3313. FIG. 116 also shows similar features to FIG. 113 but is a moredetailed view to better show the indicia 3358 and the button-hole 3303in the pocketed end 3313.

FIG. 117 shows a further detailed view of FIG. 114 to better illustratethe button-hole 3303 at the pocketed end 3313. FIG. 118 shows a furtherdetailed view of FIG. 113 to better illustrate the button-hole 3303 atthe pocketed end 3313.

FIGS. 119 to 122 show similar features to those shown in FIGS. 113 to118, however in these views the flange 3359 is pulled from thebutton-hole 3303 to better show its design. FIGS. 119 and 122 show therigidiser arm 3302 that includes the indicia 3358 on the outer surface3355 extending from the button-hole 3303 of the pocketed end 3311. FIG.122 should be understood to show a more detailed view of FIG. 119. FIGS.120 and 121 show the other rigidiser arm 3302 that may not include theindicia. FIG. 121 should be understood to show a more detailed view ofFIG. 120.

Stretching of Straps Relative to Rigidiser Arms

As can be seen in the example shown in FIG. 68, two rigidiser arms 3302are inserted into side strap portions 3315, 3316 of the strap 3301 ofthe positioning and stabilising structure 3300, the rigidiser arm 3302is held in place by the surrounding strap 3301 while at the same timethe sleeve-like configuration of strap 3301 allows at least a portion ofthe strap 3301 to stretch or move relative to the rigidiser arm 3302.Preferably, this stretchable portion is a substantial portion becauseonly at the anchor point is the strap 3301 secured to the rigidiser arm3302. In some examples, a limitation on the movement of the rigidiserarm 3302 is generally imposed when one of the ends 3319 a or 3319 b ofthe rigidiser arm 3302 moves towards and abuts against a respectivepocketed end 3311 of the strap 3301, as in FIG. 69. For example, whenthe positioning and stabilising structure 3300 is not on the patient'shead and the straps 3301 are loose, when the inserted rigidiser arm 3302moves too far towards the back strap portions 3317 a, 3317 b, its end3319 b may enter the open end of one of these back strap portions 3317a, 3317 b. As the width of the back strap portions 3317 a, 3317 b issmaller than that of the rigidiser arm 3302, the end 3319 b of therigidiser arm 3302 abuts against the respective back strap portion 3317a, 3317 b, which restricts its further movement in this direction.

The attachment of the strap 3301 to the rigidiser arm 3302 described inthe preceding section may also affect the size of head that thepositioning and stabilising structure 3300 may accommodate. In otherwords, by providing a greater length of strap 3301 along the rigidiserarm 3302 it may be possible to increase the total stretchable length ofthe positioning and stabilising structure 3300 such that even largercircumference heads may be accommodated without needing to increase thestretchability of the strap 3301. Furthermore, it may be possible tovary, along the length of the rigidiser arm 3302, where the strap 3301is connected. This would allow for an even greater range of head sizesand circumferences to be accommodated without the need to alter thestretchability of the strap 3301.

The length of the strap 3301 is from about 400 mm to 700 mm. The lengthof the strap 3301 may be about 490 mm. The strap 3301 may provide acomfortable level of headgear tension for most head sizes. There may betwo lengths or sizes of straps which are gender specific, the one forthe male population being longer than the female version. Preferably,there may be two sizes/lengths of the strap 3301 for each gender. Acomfortable level of headgear tension is from about 2 to about 5Newtons. A comfortable level of headgear tension is from about 2.2Newtons to about 4.7 Newtons. When the strap 3301 is stretched from 490mm to 526 mm for a small circumference head of a patient 1000, theheadgear tension as measured using an Instron machine is 2 Newtons. Whenthe strap 3301 is stretched from 490 mm to 662 mm for a largecircumference head of a patient, the headgear tension as measured usingan Instron machine is 4.4 Newtons. For the measurement, the button-holes3303, 3304 of the strap 3301 are attached onto clamping fixtures. Atensile testing machine with a 100 Newtons load cell is used. The strap3301 is extended and held at predetermined extension points (e.g. 90.5mm, 73 mm and 108 mm) for one minute, and the force value (in Newtons)is recorded for each extension point. Such measurement does not considerany friction of the material of the strap 3301 against the patient'sface or hair.

The length of a split region 3326 defined between the two back strapportions 3317 a, 3317 b is from about 180 mm to about 220 mm. The lengthof the split region 3326 may be 200 mm. If the length of the splitregion 3326 is not long enough, the two back strap portions 3317 a, 3317b will be unable to cup the back of the patient's head and thereforeunable to maintain their position during therapy and the headgeartension will not remain set to the patient's preference. If the lengthof the split region 3326 is too long, the two back strap portions 3317a, 3317 b will separate in front of the user's ears and be uncomfortableas they pass over the ears rather than above/around it and also itreduces the maximum angle range for the two back strap portions 3317 a,3317 b with respect to each other.

In the neutral and unstretched condition of the strap 3301, the two backstrap portions 3317 a, 3317 b have an angle θ from each other at about0° to about 10°. After donning the patient interface 3000, the two backstrap portions 3317 a, 3317 b may be split from each other such that theangle θ may be up to about 180°. This allows a maximum angular range of180° which in turn gives a large range for the reduction of headgeartension through incrementally spreading apart the two back strap portion3317 a, 3317 b. The angular range may be narrowed to a default angle of10° to a maximum angle of 120°. The patient may use one or both hands tomove the two back strap portion 3317 a, 3317 b now under tension on theback of their head, apart or together. By moving the two back strapportion 3317 a, 3317 b further apart from each other, the split region3326 enlarges, leading to a reduction in headgear tension from theunsplit range of 2.5 to 5 Newtons. The headgear tension may be reducedfrom about 30% to about 50% according to one example, or to about 40% inanother example, as measured by a load cell. In other words, for a smallcircumference head of a patient, the headgear tension may be reducedfrom 2 Newtons to 1.2 Newtons by enlarging the separation between thetwo back strap portions 3317 a, 3317 b. For a large circumference headof a patient, the headgear tension may be reduced from 4.4 Newtons to2.64 Newtons by enlarging the separation between the two back strapportion 3317 a, 3317 b.

The rigidiser arm 3302 may thus be allowed to move generallyunrestrictedly along the length of the strap 3301, attached to the strap3301, or may be adjacent one of its ends.

The discussed configurations allow, as shown in FIG. 70, the strap 3301,and thus, the positioning and stabilising structure 3300 to stretch andexpand in length. Such elongation is not limited to those portions ofthe strap 3301 that are not in contact with or parallel to the rigidiserarm 3302 but also, elongation, particularly elastic elongation of thestrap 3301, is achieved in the area of rigidiser arm 3302. This caneasily be derived from comparison of the length of the rigidiser arm3302 in FIGS. 68 and 70 (which remains the same although the strap 3301is stretched) with marks 3321 a-d, 3323 a-e visualizing the length ofthe strap 3301 with regard to the length of the rigidiser arm 3302. Itis easily derivable by comparison of FIGS. 68 and 70 that the rigidiserarms 3302 extend along marks 3321 a to 3321 c and 3323 a to 3323 d,respectively in FIG. 68 in the un-stretched state. Contrary thereto, inthe stretched state according to FIG. 70, rigidiser arms 3302 extendalong marks 3321 a to 3321 b and 3323 a to 3323 c, only. Therefrom, itbecomes clear that strap 3301 is stretched also in and along the areawhere rigidiser arms 3302 are contained in strap 3301. The rigidiserarms 3302 remain un-stretched however during stretching of the strap3301.

As will be appreciated, positioning and stabilising structure 3300 maycomprise one or more rigidiser arms 3302. While the above discussionconcentrates on the relationship of a rigidiser arm 3302 with a strap3301, it is to be noted that the example shown in FIGS. 68 to 70comprises two rigidiser arms 3302, one being provided in each respectiveside strap portion 3315, 3316 of strap 3301. The above comments,although eventually referring to one rigidiser arm 3302, thus equallyapply to two or more rigidiser arms 3302 connected to a mask frame 3310.

One possibly advantageous attribute of allowing the strap 3301 tostretch relative to the rigidiser arm 3302 as heretofore described maybe that the patient interface 3000, along with the positioning andstabilising structure 3300, may be donned and doffed by the patient 1000without the need to disconnect any straps or other connection features.This may be helpful to a patient 1000 who is using the device 3000 in adark bedroom prior to or following sleep, in that the patient does notneed to be able to see to connect or disconnect various components toattach or remove the patient interface 3000. Rather, the patient 1000may only need to simply pull on or off the patient interface 3000 andpositioning and stabilising structure 3300, and in the case of donningit may also be necessary to position the seal-forming structure 3100.However, this may all be accomplished by feel, sight being unnecessary.

It may however remain advantageous to allow disconnection of the plenumchamber 3200 or seal-forming structure 3100 from the positioning andstabilising structure 3300. For example, to clean the plenum chamber3200 or seal-forming structure 3100 it may be desirable to wash it whilenot getting the positioning and stabilising structure 3300 wet. This maybe facilitated by allowing these components to disconnect for such apurpose.

Rigidiser Arms and Mask Frame

FIGS. 47 to 60 show rigidiser arms 3302 and a mask frame 3310 accordingto a further example of the present technology.

FIGS. 47 to 49 and 54 show cross-sectional views of a rigidiser arm 3302and a mask frame 3310 and the connection therebetween, according to anexample of the present technology. Near a sharp bend 3307 of therigidiser arm 3302 an extension 3350 is connected by a joint 3356. Alsonear the sharp bend 3307 is a protruding end 3306 of the rigidiser arm3302 that may retain a pocketed end of a side strap portion 3316 of thepositioning and stabilising structure 3300. In these views the maskframe 3310 can be seen formed around a hook 3353 and an enclosablesection 3354 of the extension 3350. An opening 3335 may also be formedin the mask frame 3310 near where the mask frame 3310 surrounds theenclosable section 3354. The opening 3335 may be formed as a result ofthe overmolding process by which the mask frame 3310 is formed andsecured around the enclosable section 3354 of the rigidiser arm 3302.The rigidiser arm 3302 according to this example may be formed fromHytrel® and the mask frame 3310 may be formed from polypropylene (PP).Hytrel® is desirable for forming the rigidiser arms 3302 because thismaterial is resistant to creep. Since these materials cannot beintegrally bonded the mask frame 3310 may be overmolded to the rigidiserarm 3302 in this example to form a secure connection. It should also benoted that in this example the extension 3350 and the rigidiser arm 3302may be molded as one piece. The mask frame 3310 may be connected to therigidiser arms 3302 at respective extensions 3350 located oppositedistal free ends 3302.1. The extension 3350 may comprise a straightsection 3351 joined to a bend 3352 joined to a hook 3353. The hook 3353and a portion of the bend 3352 may form the enclosable section 3354.

It should be understood that the joint 3356 that connects extension 3350to the rigidiser arm 3302 may provide a targeted point of flexibilityand the joint may be shaped and formed to allow flexing in a desireddirection and degree. Thus, once the patient interface 3000 is donnedand the rigidiser arms 3302 are stressed by tension from straps of thepositioning and stabilising structure 3300 the rigidiser arms 3302 mayflex at the joints 3356 to allow them to retain a face framing shapewhile helping to retain the mask frame 3310 in a desired positionrelative to the patient's face.

FIGS. 50 and 51 show perspective and detailed perspective views,respectively, of rigidiser arms 3302 connected to a mask frame 3310,according to an example of the present technology. FIG. 51 further showsthe enclosable section 3354 in dashed lines and overmolded by the maskframe 3310 to secure the mask frame to the end of the rigidiser arm3302. The opening 3335 can be seen, as in FIGS. 47 to 49, forming apassage completely through the mask frame 3310 and the hook 3353 of therigidiser arm 3302.

FIGS. 52 and 53 show top and detailed top views, respectively, of a maskframe 3310 connected to rigidiser arms 3302, according to an example ofthe present technology. In FIG. 52 the dimension L indicates the lengthof the rigidiser arm 3302 in the direction shown. Preferably, thenominal length L of a rigidiser arm 3302 is 114 mm. These views showparticularly well how the joint 3356 may connect the extension 3350 tothe rigidiser arm 3302 between the protruding end 3306 and the sharpbend 3307.

FIGS. 55 to 57 show side, front, and perspective views, respectively, ofrigidiser arms 3302 and a mask frame 3310, according to an example ofthe present technology. In FIG. 55, the dimension H indicates the heightof the rigidiser arm 3302 in the direction shown. Preferably, thenominal height H of a rigidiser arm 3302 is 33 mm. The rigidiser arm3302 and the extension 3350 may be formed as one piece and thenconnected to the mask frame 3310 by overmolding the mask frame 3310 tothe enclosable section 3354 of the extension 3350 of the rigidiser arm3302. The extension 3350 accommodates nose droop by bending in apivoting manner or vertical rotates relative to the rigidiser arm 3302.Since the extension 3350 has a smaller height, has less material thanthe remainder of the rigidiser arm 3302 and is decoupled from theremainder of the rigidiser arm 3302 by the sharp bend 3307, bending ofthe extension 3350 is localised and occurs before the remainder of therigidiser arm 3302 starts to bend. This reduces the likelihood ofdisruption of sealing forces.

FIGS. 58 and 59 show partially exploded and detailed partially explodedviews, respectively, of rigidiser arms 3302 and a mask frame 3310,according to an example of the present technology. The hook 3353 and theenclosable section 3354 of the extension 3350 can be seen separated fromthe mask frame 3310. The shape of the hook 3353 and the enclosablesection 3354 may be seen in these views and it should be understood thatthese portions are formed to ensure a stronger mechanical interlock withthe mask frame 3310 when the mask frame 3310 is overmolded.Specifically, these views show that the enclosable section 3354 may beformed with flared ends at the hook 3353 to provide surfaces forretention to the mask frame 3310. In another example of the technology,the enclosable section 3354 may include an opening for restraining therigidiser arm 3302 within the mold tool(s) during overmolding of themask frame 3310. A mold tool may be inserted through this opening tostabilize the rigidiser arm 3302 as the mask frame 3310 is overmoldedaround the rigidiser. This may be advantageous because the pressures ofovermolding may cause the rigidiser arm 3302 to shift during the moldingprocess such that a less than ideal mechanical interlock with the maskframe 3310 would be formed.

FIG. 60 shows a perspective view of a rigidiser arm 3302 according to anexample of the present technology. It shows the rigidiser arm 3302 priorto permanent connection with the mask frame 3310. As discussedimmediately above, the rigidiser arm 3302 may include a hook 3353 and anenclosable section 3354 to allow for connection to the mask frame 3310via mechanical interlock. This permanently connects the rigidiser arm3302 to the frame 3310. By having the rigidiser arm 3302 and the frame3310 permanently connected together, it means that there are lessdetachable parts and reduced likelihood of losing a part duringassembly/disassembly of the patient interface 3000 when cleaning.

Positioning and Stabilising Structure on a Patient

FIGS. 71 to 73 show an example of the present technology. Here, thepositioning and stabilising structure 3300 comprises a strap 3301 withside strap portions 3315, 3316 and a back strap portion 3317 comprisingtwo back strap portions 3317 a, 3317 b running in parallel along theback of a patient's head. The positioning and stabilising structure 3300comprises two rigidiser arms (not shown), each contained in a respectiveside strap portion 3315, 3316 of the sleeve- or tube-like strap 3301.Rigidiser arms 3302 impart a predetermined shape or desired shape and/orrigidity to the strap 3301, and thus, the positioning and stabilisingstructure 3300. For example, the side strap portions 3315, 3316 of thestrap 3301 have a certain curvature for following a desired contouraround a patient's face (see curvature at reference numeral 3323 inFIGS. 52, 54, 58, and 60), which is achieved by the provision ofrespectively shaped rigidiser arm 3302. In the example shown, thepositioning and stabilising structure 3300 is connected to the frame3310, plenum chamber 3200 or seal-forming structure 3100 for providingbreathable gas such as air, eventually pressurized breathable gas, to apatient's airways. In the shown example, such breathable gas is providedvia the hose or tube 4180 connected to patient interface 3000. The tube4180 may be connected at its other end (not shown) to a source ofbreathable gas, such as a blower or ventilator for providing pressurizedbreathable gas. The patient interface 3000 may comprise a frame portionor frame 3310 for imparting structural integrity to the patientinterface 3000 and/or for connecting to the positioning and stabilisingstructure 3300. The positioning and stabilising structure 3300 may beconnected to the frame 3310, plenum chamber 3200 or seal-formingstructure 3100 via a separate connector means (not shown) provided onstrap 3301 and/or rigidiser arm 3302.

FIGS. 74 to 77 show similar features to those shown in FIGS. 71 to 73,however the examples shown in FIGS. 74 to 76 and 77 depict a differentconnection between the positioning and stabilising structure 3300 andthe mask frame 3310. At each end of the side strap portions 3315, 3316there is a pocketed end 3311, 3313 as shown in FIGS. 65 and 81. Thesepocketed ends 3311, 3313 are retained on the rigidiser arms 3302 (notvisible in these views because they are within the side strap portions3315, 3316) by the protruding end 3306 of respective rigidiser armsshown, for example, in FIGS. 47 to 60. Although not visible in FIGS. 74to 77, it should be understood that, in this example, end welds 3311.1,3313 depicted in FIG. 81 serve to close the pocketed ends 3311, 3313 sothat they may be retained against the protruding ends 3306. Therigidiser arms 3302 are then permanently and mechanically secured to themask frame 3310 by overmolding, for example, as described with referenceto FIGS. 47 to 60.

Split Back Straps of Positioning and Stabilising Structure

According to one aspect, the structure of strap 3301 and positioning andstabilising structure 3300 is of advantage. In particular, the provisionof two elastic straps or back strap portions 3317 a, 3317 b at the backallows the head to be cupped and the tension vector(s) to be adjusted bysuitably positioning them, e.g. by spreading. The provision of two backstrap portions 3317 a, 3317 b also allows better support and stability,as well as increased flexibility in avoiding specifically sensitiveregions of the back of the head. The back strap portions 3317 a, 3317 bare intended to cup the head at the calvaria to maintain position andengagement. In one example, depending on the particular head shape of apatient and the amount of splitting of the back strap portions 3317 a,3317 b, the upper back strap portion 3317 a is to be located proximal tothe parietal bone and the lower back strap portion 3317 b is to belocated proximal to the occipital bone or superior fibers of thetrapezius muscle (i.e. near the nape of the neck or nucha). The lowerback strap portion 3317 b may be configured to engage the head of thepatient at a position on or lower than the external occipitalprotuberance. In contrast to headgear of prior masks which requirematerial length adjustment (shortening or lengthening), the tensionprovided by the positioning and stabilising structure 3300 is adjustablesimply by opening or closing the relative angle between the two backstrap portions 3317 a, 3317 b. To reduce headgear tension, the two backstrap portions 3317 a, 3317 b are separated further apart on the back ofthe head when the patient interface 3000 is worn. To increase headgeartension, the two back strap portions 3317 a, 3317 b are brought closertogether. This manner of adjustment is advantageous over notched strapswhich only permit preset incremental adjustment of headgear tension,Velcro™ (unbroken loop fabric) straps which require several attempts atfastening and unfastening until the desired headgear tension isobtained, or looping a strap through a buckle that is easier to increasethan decrease headgear tension because of the motion of pulling thestrap through the buckle for tightening. Also, patients 1000 are afraidto get the headgear tension wrong or to change the headgear tension.

The two smaller straps or back strap portions 3317 a, 3317 b at the backof the head may be equal in length and not adjustable except through theelasticity of the material or through increasing both in tightnessequally by shortening the total length at the side strap portions 3315,3316 of the positioning and stabilising structure 3300. For example, asliding mechanism (not shown) may be provided that allows the straps3301 to be overlapped to a different extent, thus changing the overalllength of the positioning and stabilising structure 3300.Non-independently adjustable strap lengths allow the two back strapportions 3317 a, 3317 b to naturally center themselves on the crown ofthe head. The two back strap portions 3317 a, 3317 b may be symmetricalor asymmetrical. In other words, the upper back strap portion 3317 a maynaturally settle at the top of the head, while the lower back strapportion 3317 b may naturally settle at the back of the head near orbelow the occipital lobe. This may reduce the possibility of manuallyover tightening one strap to compensate for the other being too looseresulting in a misfit of the positioning and stabilising structure 3300.This, again, might not only lead to discomfort but also negativelyinfluence therapy compliance. The aggregated width of both back strapportions 3317 a, 3317 b may be substantially equal to the width of aside strap portion 3315. This is aesthetically pleasing as well asproviding a visual indicator to the patient to adjust the back strapportions 3317 a, 3317 b when donning the patient interface 3000.Although two back strap portions 3317 a, 3317 b have been described,more are possible which may provide differing degrees of adjustment ofheadgear tension. When the strap 3301 is in the neutral state andunstretched, the two back strap portions 3317 a, 3317 b are partiallyseparated such that a gap exists between them for inviting or indicatingto the patient to adjust the back strap portions 3317 a, 3317 b whendonning the patient interface 3000. This improves the intuitiveness foradjusting headgear tension, and visually indicates how the headgeartension may be adjusted that is sometimes lacking in prior masks.

As indicated above, two or more joints could be provided creating thepositioning and stabilising structure 3300 from three, four or moreseparate straps rather than the strap 3301 being one continuous piece.This might complicate the assembly, but may simplify the manufacturingprocess. Joints may be placed at the bifurcation point 3324 between theside strap portions 3315, 3316 and two back strap portions 3317 a, 3317b or centered at the back. The joints may be sewn, welded, glued, orover molded and could incorporate a high friction material to helpreduce movement on the head. High friction materials may include padprinting, silicone printing to increase relative surface frictionbetween the straps 3301, 3317 a, 3317 b and the patient's skin or hairin order to maintain position of the straps 3301, 3317 a, 3317 b on thepatient's head. The high friction materials may be present only on thepatient contacting surface of the back strap portions 3317 a, 3317 bsince the rigidiser arms 3302 may perform some or most of the functionof maintaining position of the side strap portions 3315, 3316 relativeto the patient's face.

High friction materials may also be added to the inside surface of theback and side strap portions 3315, 3316, 3317 a, 3317 b, to reduce thestraps from slipping against the patient's face or hair. For the arms orside strap portions 3315, 3316 this would help the positioning andstabilising structure 3300 stay on the cheeks and at the back strapportion 3317 it could stop the positioning and stabilising structure3300 from sliding across the back of the head. Such material may beprinted, cast or molded onto the surface or incorporated into joints,sewing or welding processes as mentioned above. Another way to reducestrap slippage is to have elastic yarns protruding from the textilematerial.

Instead of being inserted from the button-holes 3303, 3304 located closeto the mask frame 3310, as shown in FIG. 65, the rigidiser arm 3302could optionally be inserted from an opening 3308 located proximal tothe bifurcation point 3324 where the positioning and stabilisingstructure 3300 bifurcates. Once the rigidiser arm 3302 is inserted, theelasticity of the material could be used to hook back the rigidiser arm3302 inside the opening of one of the small back strap portions 3317 a,3317 b (upper or lower). This may prevent the rigidiser arm 3302 frommoving, thus securing it in place. Otherwise the button-holes 3303, 3304could be sewn, molded or otherwise closed permanently in order to trapthe rigidiser arm 3302 inside the strap 3301.

The split region 3326 at the back may include two, three or more strapsfor stability. A positioning and stabilising structure 3300 similar tothe described, may be used with full face (covering the nose and mouth)or nasal masks also. Other positioning and stabilising structures ofprior masks that may have two or more straps at the back (which may bethe same width as the side straps) where the lower back strap typicallyengages against the head of the patient at a position on or lower thanthe external occipital protuberance. Such back straps are notstretchable or elastic, but may be length adjustable, and the backstraps may be biased to return to a default angle to avoid crinkling andtwisting at the convergence point with a single side strap. For example,the default angle may be 45° for the split between two back straps inorder to cup and engage the patient's head, and the pivoting of the backstraps relative to each other are for donning and doffing the patientinterface to fix the patient interface into a position to providetension to a seal-forming structure against the patient's face. The twoback straps are biased to return to the 45° angle and therefore onlyserve the function of cupping the back of the patient's head forstability of the patient interface and cannot maintain any angle thatdeviates from the 45° angle.

With the use of the present technology, the provision and use ofrigidiser arms 3302 may affect the stretchable length of the strap 3301.This may allow the positioning and stabilising structure 3300 to fit alarge range of head sizes. This may effectively be a “one size fitsmost” positioning and stabilising structure 3300, which means that theout of the bag positioning and stabilising structure 3300 is more likelyto fit a patient even if the patient has not previously tried or usedthe positioning and stabilising structure 3300. The present technologymay provide a positioning and stabilising structure 3300 that allowseasy donning and doffing of the patient interface 3000. In particular,this may mean that, unlike some other positioning and stabilisingstructures, the tension settings do not have to change and/or are notlost when the mask 3000 is doffed. The rigidiser arms 3302 may define adesired shape that ensures that there is clearance around the eyes andears for comfort and visibility. The textile of the strap 3301 may allowthe skin to breathe and sweat naturally without silicone, foam orplastics creating and retaining surface heat and condensate fromperspiration.

The provision of two elastic straps 3317 a, 3317 b at the back of thestrap 3301 may allow the patient's head to be cupped and thedistribution of the applied force to be adjusted by spreading them andindependently changing their position. The two smaller back strapportions 3317 a, 3317 b at the back of the head may be equal in lengthand not adjustable except through the elasticity of the material orthrough increasing both in tightness equally by shortening the totallength at the straps of the positioning and stabilising structure 3300.

Flexible Joint 3305

FIGS. 19, 71 to 73, 75, 76 and 166 also show the connection of thepositioning and stabilising structure 3300 to the frame 3310 associatedwith the plenum chamber 3200. Particularly, the joint 3305 at therigidiser arm 3302 and the frame 3310 may be flexible and/or elasticallydeformable. Thus, when donned by the patient 1000, the seal-formingstructure 3100 may be able to accommodate a variety of nasolabial angles(e.g., as shown in FIG. 2e ). It should be understood, therefore, thatthe flexibility of this joint 3305 may allow the frame 3310, plenumchamber 3200, and other associated components to move about a number ofaxes relative to the rigidiser arms 3302. In one form of the presenttechnology, the frame 3310 and the plenum chamber 3200 may be rotatablevia the flexible joint 3305 about an axis defined between respectiveends of the rigidiser arms 3302. By such an arrangement, theseal-forming structure 3100 may be able to be angled against theinferior region of the patient's 1000 nose over a wide range of possiblenasolabial angles.

As can be seen in FIGS. 18, 19, 75, 76 and 166, the seal-formingstructure 3100 is retained against the underside of the nose of thepatient 1000, one example, against the patient's airways such as thenares. Proper location of the seal forming structure 3100 is asignificant factor in achieving an effective seal of the frusto-cone3140 against the patient's nares such that the leaking of pressurizedgas is minimized with minimal retention forces. As the frusto-cone 3140may extend axially from the stalk 3150 of the seal forming structure3100, it may be advantageous to allow a degree of flexibility in theorientation of the patient interface 3000 with respect to the patient'snose to achieve an optimal seal. Such flexibility may be advantageousbecause patients may have a variety of nasolabial angles (see FIG. 2e )that may need to be accommodated by a common patient interface. Thisflexibility may be accomplished in an exemplary patient interface 3000by providing a flexible joint 3305. In an example of the presenttechnology, the flexible joint 3305 may be positioned between the frame3310 and the rigidiser arm 3302. In such an exemplary arrangement, theframe 3310 may be comprised of a material that facilitates flexing atthe flexible joint 3305 with rigidiser arm 3302 of the positioning andstabilising structure 3300. In an alternative arrangement, it may be therigidiser arm 3302 that may flex via the extension 3350 to allow properlocation of the seal-forming structure 3100 against the underside of thepatient's nose. Additionally, it is also envisioned that flexing mayoccur partially at both parts. In any of the envisioned arrangements thedesired result is that the patient interface 3000 may be able to rotatewith respect to the underside of the patient's nose such that variousnasolabial angles may be accommodated. This flexibility provided by theflexible joint 3305 allows the trampoline 3131 to be more effective inproviding a comfortable force against the patient's nares or nose.Without the flexible joint 3305, the trampoline 3131 would be lesseffective at accommodating a variety of alar angles and maintainingstability since the stalks 3150 and plenum chamber 3200 would already bein a partially or fully collapsed state when the tension from thepositioning and stabilising structure 3300 holds the seal-formingstructure 3100 in sealing position against the patient's airways.

This flexible joint 3305 may be provided by forming the frame 3310and/or the rigidiser arms 3302 from a material having a modulus ofelasticity sufficient to allow flexibility in the joint 3305, whilemaintaining sufficient stiffness to ensure an effective seal.Additionally or alternatively, the frame 3310 and/or the rigidiser arms3302 may be shaped structurally to allow for flexibility in this region.In other words, the frame 3310 and/or the rigidiser arms 3302 may beshaped to allow the requisite amount of flexibility in the region of thejoint 3305. This may be accomplished by removing portions of thesestructures such that their stiffness is reduced to allow flexing.

A further possible advantage of this aspect of the technology may bethat it reduces the bending moment associated with the rigidiser arms3302 and the frame 3310. As shown in FIGS. 19, 71 to 73 and 75, therigidiser arms 3302 may be shaped to conform to the contours of thepatient's face. Also, when the seal-forming structure 3100 engages withthe patient's nares, they may cause displacement of the frame 3310 dueto the relatively limited amount of flexibility between the seal-formingstructure 3100, the plenum chamber 3200, and the frame 3310, which areheld against the nose by the positioning and stabilising structure 3300.By providing a flexible joint 3305 between the frame 3310 and therigidiser arms 3302, the bending moment associated with these structureswhen the patient interface 3000 is donned by the patient may be reducedbecause some of the associated forces may be dissipated into the flexingof the joint. This may be advantageous because the patient interface3000 would then be subjected to less force during use to reduce wear andtear. Also, by dissipating these forces into the bending of the flexiblejoint 3305, bending of the rigidiser arms 3302 and/or the frame 3310 maybe reduced. This may be advantageous because if the rigidiser arms 3302are shaped to conform to the face of the patient, then bending them mayreduce the conformity, resulting in discomfort to the patient. The samemay be true for bending of the frame 3310 and bending of the frame 3310may also cause the seal-forming structure 3100 to be displaced from thepatient's nose.

It should also be understood that in the arrangement discussed above, itmay be advantageous to stiffen the rigidiser arms 3302. By forming therigidiser arms 3302 from a material that is sufficiently stiff and/orshaping the rigidiser arms 3302 such that they are sufficiently stiff,it may be possible to ensure that the flexible joint 3305 does not allowthe seal-forming structure 3100 to displace from the patient's nose. Inother words, a proper fit and effective seal may be accomplished bysufficiently stiff rigidiser arms 3302 that maintain the desired degreeof conformity to the patient's face while allowing sufficientdisplacement of the seal-forming structure 3100 such that it can engagethe patient's nose and provide an effective seal. The rigidiser arms3302 may be formed from Hytrel® with a flexural modulus of 180 MPa at23° C. and a tensile modulus of 180 MPa (26). It should also beunderstood that in one aspect of the technology, the patient interface3000 may be structured such that elastic deformation takes place only atthe seal-forming structure 3100 and at the flexible joint 3305 betweenthe frame 3310 and the rigidiser arms 3302.

In the example of the present technology described without a flexiblejoint 3305, the extension 3350 of the rigidiser arm 3302 performs asimilar function to the flexible joint 3305 as described above.

Tension Vectors of Positioning and Stabilising Structure

As mentioned above, the exemplary positioning and stabilising structure3300 may advantageously locate the headgear tension vectors with respectto the patient's head such that the compression vectors associated withthe seal-forming structure 3100 are properly aligned with the nose ornares of the patient. As shown in FIGS. 72, 73, 75 and 76, a vector V isdepicted to indicate an exemplary direction and magnitude of a forcethat urges the seal-forming structure 3100 against the nose of thepatient 1000 in use. By attaching the exemplary positioning andstabilising structure 3300 operatively to the seal-forming structure3100, the tension of the positioning and stabilising structure 3300 whenworn by the patient 1000 may be sufficient to urge the patient interface3000 against the nose or nares of the patient 1000 with a force havingthe direction and magnitude of the vector V. The concept of the vectorsmay be explained as follows. To properly and/or effectively form a sealabout the nares of the patient 1000, when using nasal pillows 3130 asdepicted in this example of the technology, the seal-forming structure3100 should be urged against the patient's nares in a directionsubstantially coaxial to the longitudinal axes of respective stalks 3150of the seal-forming structure 3100. The magnitude of the force must alsobe sufficient to allow the seal-forming structure 3100 to seal aroundthe nares, but not so great as to cause discomfort or deformation of therelatively soft seal-forming structure 3100. Therefore, a force of themagnitude and direction depicted as the vector V must be provided to theseal-forming structure 3100. However, it is not ideal to have straps3301 draped across the eyes and along the sides of the patient's nose oracross the ears. This may be uncomfortable and disruptive to the patient1000. Two point force and vector control allows the strap 3301 to gentlystabilise the mask 3000 and pull the nasal pillows 3130 into place andform a pneumatic seal with the patient's airways.

To overcome this problem of needing to provide sealing forces of arequisite direction and magnitude while displacing them from certainregions of the patient's face, the rigidiser arms 3302 and/or frame 3310described above may be provided. The rigidiser arms 3302 and/or frame3310 may act as an intermediary for transferring tension forces from thepositioning and stabilising structure 3300 to the seal-forming structure3100, while allowing the straps 3301 to be directed away from thepatient's eyes. In other words, the positioning and stabilisingstructure 3300, by virtue of being in tension, may generate a force atone end of a respective rigidiser arm 3302 and/or frame 3310, whichbeing sufficiently stiff, transmits this force having an equivalentdirection and magnitude to its opposite end where the seal-formingstructure 3100 is located. Thus, the seal-forming structure 3100 may beurged against the patient's nose to form an effective seal. Said anotherway, the rigidiser arms 3302 and/or the frame 3310 serve to structurallydecouple the positioning and stabilising structure 3300 from theseal-forming structure 3100 while continuing to maintain sealing forcesof an adequate direction and magnitude.

As described above, the straps 3301 of the positioning and stabilisingstructure 3300 may surround the rigidiser arms 3302 in certain examples.To facilitate the force decoupling described in the preceding paragraphswhile maintaining this sheath-like arrangement of the straps 3301 andrigidiser arms 3302, the rigidiser arms 3302 may comprise a smoothsurface along at least a portion thereof. By providing a smooth surfacealong the rigidiser arms 3302, the straps 3301 of the positioning andstabilising structure 3300 may extend and/or compress along therigidiser arms 3302 in a relatively free and/or low friction fashion. Inother words, the straps 3301 float over the rigidiser arms 3302 exceptat the pocketed ends 3311 where it is secured to the rigidiser arms3302. Moreover, by reducing friction of the positioning and stabilisingstructure 3300 along the rigidiser arms 3302, extraneous and undesiredforces may be avoided, which may in turn result in a loss or disruptionof the pneumatic seal of the seal-forming structure 3100 and/or anuncomfortable fit.

Some positioning and stabilising structures of prior masks that have amulti-layered laminated strap where there are layers made from differentmaterials providing different degrees of flexibility permanentlylaminated to each other. Other positioning and stabilising structures ofprior masks use stitching or adhesives to permanently connect themulti-layered strap together. In contrast, the positioning andstabilising structure 3300 of the present technology has a strap 3301that is releasably engageable with the rigidiser arm 3302. This permitsseparate washing of the strap 3301 from the rigidiser arm 3302 and frame3310. The releasable engagement is provided in a small area localisedregion (the edge of the rigidiser arm 3302 proximal to the frame 3310)using a pocketed end 3311 of the strap 3301 which permits stretch ofsubstantially the entire length of the strap 3301 from the point ofconnection with the frame 3310. Other positioning and stabilisingstructures of prior masks may use an adjustment buckle or Velcro™ toadjust the length of one or more headgear straps (usually by shorteningthe length) in order to adjust the headgear tension of the patientinterface 3000 on the patient's face. In contrast, the positioning andstabilising structure 3300 of the present technology does not requirelength adjustment to adjust the headgear tension and is particularlybeneficial for patients with arthritic hands who may lack fine motorskill to be able to properly an adjustment buckle or Velcro™ forheadgear tension adjustment, especially in a darkened room.

Manufacturing the Strap

A positioning and stabilising structure 3300 is manufactured to shape(e.g., formed in one piece to shape otherwise known as“fully-fashioning” without the need to cut away any substantial amountsof material) thereby producing little or no waste material.Alternatively, the positioning and stabilising structure 3300 may bedivided into segments that are each manufactured to shape separately(e.g., by knitting) and then attached to one another. FIG. 132demonstrates a single, unitary seamless structure having at least tworegions (e.g. the crown portion or rear portion 210 and straps 220),wherein the at least two regions extend from a junction (the junctionbeing the connection between the straps 220 and the rear portion 210),where the straps 220 extend at a different angular orientation to therear portion 210. The rear portion 210 and straps 220 are formed in acontinuous process (i.e. the material that makes up the component andthe shape of the component are formed in a single step)—this isdifferent to a process where a sheet of material is made and then cut toshape (this would not be considered a single step). FIG. 132 also showsthat the straps 220 branch out or extend at a different angle ordirection to the rear portion 210, without requiring seams or additionalformation steps.

A knitted component such as a positioning and stabilising structure 3300is defined as being formed of “unitary knit construction” whenconstructed as a one-piece knit element that is substantially free ofadditional stitching or bonding processes.

As shown in FIG. 133, the straps 220 may be formed (e.g., by warpknitting, circular knitting or 3D braiding) as a continuous piece thatis subsequently cut as this procedure may further increase manufacturingefficiency.

Knitting various positioning and stabilising structure sections in acontinuous manner may be advantageous as there are no or very fewadditional manufacturing steps that would be required to sew, fuse,adhere or otherwise attach adjoining sections. As a result, themanufacturing process may have reduced steps, the amount of materialwaste is reduced, there would be virtually no seams in the positioningand stabilising structure 3300 between the adjoining sections, and thepositioning and stabilising structure 3300 made of a fabric withoutdistinctive joins or seams may be more comfortable for patients.

Techniques

A number of techniques can be used in accordance with the presenttechnology to manufacture a positioning and stabilising structure 3300to shape with little or no waste material. The technique may produce apositioning and stabilising structure that is a single, unitary,seamless structure. Techniques that may produce a single unitaryseamless structure include mechanical manipulation of yarn includinginterlooping (such as knitting), interweaving and/or intertwining(including braiding, knotting and crocheting). An alternative techniqueof 3D printing may also create a positioning and stabilising structurehaving a unitary, seamless structure.

A manufacturing technique in accordance with the present technology mayhave one or more of the following features: (1) produces little or nowaste; (2) produces a positioning and stabilising structure that iscomfortable for the patient; (3) produces a positioning and stabilisingstructure that is conformable; (4) produces a positioning andstabilising structure that is breathable; (5) produces a positioning andstabilising structure that may minimize facial marking; and/or 6)produces a positioning and stabilising structure that is lightweight.

Interlooping—Knitting

In accordance with an example of the present technology, a positioningand stabilising structure 3300 may be formed by interlooping such asknitting (e.g., threading yarn or thread to form a knitted fabric). Thepositioning and stabilising structure 3300 may be formed by flatknitting or circular knitting, however other forms of knitting may alsobe possible. Flat knitting and circular knitting may be advantageous asthey are able to create a positioning and stabilising structure 3300with a unitary, seamless structure. Flat or circular knitting machinesmay be utilized to create a weft knit or a warp knit. A variety ofknitting processes including circular knitting and warp- or weft-flatknitting, may be utilized to manufacture the positioning and stabilisingstructure component or components. Flat knitting may have someadvantages, including but not limited to (1) the ability to locatefloating yarns within, for example, a positioning and stabilisingstructure strap, in order to provide extra cushioning or bulk, and/or(2) the ability to include extra loops of yarns on either the upper orlower surface of the positioning and stabilising structure strap, thuscreating the effect of a soft terry cloth material, for example, orcreating an unbroken loop fabric for engagement with a hook tapefastener, and/or (3) the ability to knit a 3D dimensional spacer fabricconstruction adjacent to double-faced knit construction within a singleunified positioning and stabilising structure construction.

The positioning and stabilising structure 3300 may be formed primarilyfrom multiple yarns that are mechanically manipulated through aninterlooping process to produce a single unitary structure havingvarious sections with different physical properties.

FIG. 134 illustrates the wale of a weft knit fabric 64, or the directionthat the loops of one thread join to a loop of another thread. Thecourse 85, or the direction of the loops from a single thread is shownin FIG. 135. FIGS. 136 and 137 illustrate a basic closed loop warp knit90. FIG. 138 illustrates an example of a warp knit tricot jersey fabricstructure in which a yarn is knitted in a vertical direction in azig-zag manner, capturing other warp yarns, with the wale runningsomewhat parallel to the course.

Referring to FIGS. 136 to 139, a warp knit 90, 90-1 comprises the walesand courses running parallel to one another, while in a weft knit 100the wales run perpendicular to the course. The positioning andstabilising structure 3300 of the present technology may be formed byeither warp knit or weft knit. A warp knit, for example tricot, raschelor locknit, is typically more resistant to runs, easy to machine, andmay utilize multiple yarns (allowing for the use of multiple colors oryarn types). A weft knit 100 can be formed with a single yarn; however,use of multiple yarns is also possible. The positioning and stabilisingstructure 3300 of the present technology may be constructed of a warpknit or a weft knit.

Knitted fabrics may have different stretchability characteristicscompared to woven fabrics. Knitted fabrics are typically more flexiblethan woven fabrics, which may only stretch in one direction (dependingon the yarn they are made from), and therefore may provide a morecomfortable fit for the patient. Knitted textiles may be constructed insuch a way that the fabric has a two-way stretch—i.e. a first yarnoriented in a first direction has a lower flexibility than a yarnoriented in a second direction. This arrangement may be desirable alongthe straps of the positioning and stabilising structure 3300 such thatthe straps can stretch along their length but not across their width, orvice versa. Alternatively, the knitted textile may have a four-waystretch i.e. yarn in a first direction and a second direction and bothare flexible such that application to a strap would allow stretch inboth lengthwise and crosswise directions.

The example of FIG. 142 shows a strap 1200 having a grain or course1250, and illustrates how the direction of the grain or course affectsstretch. The knitted fabric will tend to stretch more readily in thedirection of the course. Therefore, the positioning and stabilisingstructure 3300 may be designed to stretch in certain directions and bemore resistant to stretch in other directions. For example, the strap1200 will tend to stretch in its width direction A (from the patient'sface to the back of the head) and may have limited stretch along thelength of the strap. This configuration may increase stability of thepositioning and stabilising structure 3300 in the lengthwise directionwhile increasing fit range. The strap 1200 may be configured to stretchin certain directions and be resistant to stretch in other directions inorder to better enable the strap 1200 to hold a mask assembly on apatient's face in a manner that enhances the seal with the patient'sface.

Referring to FIGS. 140 and 141, a knitted strap 1105 includes a topportion 1102, a rear portion 1104, and a lower portion 1106. The lowerportion 1106 may bifurcate or branch out at a junction to form the topportion 1102 and the rear portion 1104. The angular orientation of thetop portion 1102 may be different compared to the rear portion 1104 e.g.the top portion 1102 may extend at about 30-110 degrees, or about 90degrees or perpendicular to the rear portion 1104. The direction of theknit, or the grain or course 1150 of the knit, may be altered to adjustthe shape or stretch of the fabric in certain areas. For example, thegrain or course 1150 may be configured to curve the strap at a cheekregion to avoid obstructing the patient's eyes. Further, as shown inFIG. 141, the grain or course 1150 may curve, as shown by the arrows B,to a split thereby forming the top portion 1102 and the rear portion1104. Such configurations of the top portion 1102 and the rear portion1104 may stabilize the straps in position on the patient's head and thusbetter enable the knitted strap 1105 to hold a mask assembly on apatient's face in a manner that enhances the seal with the patient'sface.

The knitted strap 1105 may support a patient interface 3000 (e.g., anasal mask) on the patient's face. A connector 1120 may be used toattach the strap 1105 to the patient interface 3000, and an air circuit4170 may deliver breathable gas to the patient's airways via the patientinterface 3000. In the illustrated example, the patient interface 3000is positioned under the patient's nose and seals against the externalsurfaces of the patient's nose.

The positioning and stabilising structure 3300 of the present technologymay further comprise a pocket, tunnel, layers and/or ribs. Suchpositioning and stabilising structures 3300 may be formed in one pieceby circular or flat knitting. The pockets or tunnels may be reinforcedwith materials having a higher stiffness or rigidity than the knittedtextile, thereby rigidising the positioning and stabilising structure3300. Rigidising the positioning and stabilising structure 3300 maybetter stabilize the mask in position on the user's face. Materials usedfor rigidising the positioning and stabilising structure 3300 mayinclude plastics such as nylon, polypropylene, polycarbonate, or higherstiffness textiles such as braided ropes. The rigidising of thepositioning and stabilising structure 3300 may be positioned at boneyregions of the patient's head, for example the cheeks, occiput or crown.The reinforcing structure may be inserted during the knitting process,for example, a stiffer or flatter yarn or a rigid polymer element may beinserted into the knit construction, during or after the knittingprocess. The strands or rigid components would function to withstandtension and bear the stresses e.g., due to tightening of the positioningand stabilising structure straps for therapy, or to stabilise the maskbetter, or would assist to act as coupling or fastening agents to attachthe positioning and stabilising structure piece(s) to the maskinterface.

Alternatively, the pockets or tunnels may be cushioned to add comfort.For example, pockets or tunnels may be filled with foam, gel, floatingyarn, looped yarn or other cushioning material.

The positioning and stabilising structure 3300 may be formed by flatknitting or circular knitting, wherein the positioning and stabilisingstructure 3300 has selvedges. That is, the positioning and stabilisingstructure 3300 may be formed to have a finished configuration such thatthe ends of the yarns used to construct the positioning and stabilisingstructure 3300 are substantially absent from the edges of thepositioning and stabilising structure components. An advantage offashioning the positioning and stabilising structure components to thefinished shape is that the yarns are not being cut, and are thus lesslikely to unravel and may require fewer finishing steps. By formingfinished edges, the integrity of the positioning and stabilisingstructure 3300 is maintained or even strengthened and fewer or nopost-processing steps are required to either (1) prevent unravelling ofthe positioning and stabilising structure component and/or (2) create anedge that is distinct yet soft (such as in ultrasonically cutting andsealing a ‘soft edge’ on a fabric-foam-fabric laminate material) and/or(3) enhance the aesthetic and durability characteristics of thepositioning and stabilising structure 3300.

The positioning and stabilising structure 3300 of the present technologymay be formed by a regular or irregular pique knit. A pique knit willorient a first yarn on the right side (non-patient contacting side thatis visible once the positioning and stabilising structure 3300 isdonned) and a second yarn on the wrong side (the patient contacting sidethat is not visible once the positioning and stabilising structure 3300is donned). That is, the yarn exposed on the right side may be differentto the yarn exposed on the wrong side. For example, the yarn on theright side may have a pleasant visual appearance and the yarn on thewrong side may have a nice hand feel for contacting the patient's skin.Alternatively, or in addition, the yarn on the right side may have afirst moisture wicking property and the wrong side may have a secondmoisture wicking property. For example, the yarn on the right side mayhave a high percentage of microfiber having a first moisture wickingproperty and the wrong side may have a high percentage of non-microfiberhaving a second moisture wicking property.

The positioning and stabilising structure 3300 may be formed as aunitary knit structure which may also be uniform in material andproperties, for simplicity, but it may be formed as a unitary structureincluding various sections that have different physical properties,joined in a seamless manner. The various sections may exhibit, forexample but not limited to, different degrees of strength, abrasionresistance, wear resistance, flexibility, enhanced durability, higher orlower moisture absorption (moisture absorbability), moisture-wickingability, water affinity, breathability or air-permeability, liquidpermeability, stretch or stretch-resistance, compressibility, cushioningability, support, stiffness, recovery, fit, and form. The varioussections may be constructed to exhibit variations in directionalstretch, such as four-way stretch, or bi-directional stretch, a tailoredlevel of stretch resistance, or no stretch. This may be achieved by, forexample but not limited to, selecting a particular yarn or knitconstruction type.

The positioning and stabilising structure 3300 as a unified seamlessstructure may be formed in one piece with uniform characteristics, orfrom two or more sections with varying characteristics. The two or morepositioning and stabilising structure sections may differ by way ofusing two or more different yarns of different twist, denier, fibrecomposition, etc., thus imparting different physical properties to thepositioning and stabilising structure 3300. The two or more positioningand stabilising structure sections may differ by way of using two ormore various knit stitch types, thus imparting unique physicalproperties to the two sections.

Whereas one region may incorporate, for example, elastane or PBT(Polybutylene terephthalate polyester) to enhance stretch, the otherregion may incorporate, for example, nylon or polyester to enhancedurability. Similarly, while one region of the positioning andstabilising structure 3300 may incorporate yarn with one denier, theother region may include a yarn with a greater or reduced denier, crimpor texture, in order to customize the cushioning, thickness or bulk.

The two or more sections within a positioning and stabilising structureconstruction may be connected by using tuck stitches or other knitstitches that, for example, join a first section to a second section ina seamless manner. This would be achieved by knitting the first section,then knitting the tuck stitches between the first knitted section and asecond knitted section, then knitting the second section. The tuckstitches are utilized to seamlessly connect sections between wales,especially when using a narrow-tube circular knitting machine.

The positioning and stabilising structure piece may be finished withouta seam. If it is made with an un-dyed yarn, this may be achieved byfinishing the knitting process with a yarn that contains water-solublefibres. The water-soluble fibers permit the fabric to shrink in thedyeing process and provide a neatly-finished edge, eliminating the needto create an additional seam on the edge.

In order to enhance manufacturing efficiency, knitting machines may alsobe utilized to form a series of joined positioning and stabilisingstructure components, such as straps or crown components. That is, theknitting machines may form a single component that includes a pluralityof positioning and stabilising structure pieces. Each of the positioningand stabilising structure segments may have substantially identicalshapes and sizes. Alternatively, each of the positioning and stabilisingstructure pieces may even have different shapes and sizes, which may beprogrammed in sequence. Moreover, a knit release area (which may consistof, for example but not limited to, dissolvable yarns, loosely knittedyarns, finer denier yarns or easy-to-tear placeholder yarns) may beknitted into the series of positioning and stabilising structurecomponents in order to allow the various positioning and stabilisingstructure parts, for example, straps, to be separated without the needfor cutting operations.

Variable Thread Count

In another example, the thread count may vary across the fabric toenhance comfort, fit and/or performance. For example, the thread countmay be higher in regions requiring greater stiffness (e.g., cheekregion, occiput). In regions (e.g., along the straps) where a lowerstiffness is desired, however, the thread count may be lower therebypermitting the material to flex more easily.

The thread count, and therefore the stiffness, may be determined by thetype of yarn, the type of stitch (e.g., a criss-cross stitch may bestiff), and the distance between stitches.

Yarn

Yarn may be utilized to create the positioning and stabilising structure3300 of the present technology. The yarn may be synthetic, and may betwisted or textured, and could be made from, but not limited to nylon,polyester, acrylic, rayon, or polypropylene. The yarn could be aconventional staple yarn, a microfiber yarn, or combination of both. Theyarn may incorporate an elastane fiber or filament to provide stretchand recovery properties, such as fibers bearing the LYCRA trademark fromthe DuPont Company. The yarn may be made of synthetic materials, ornatural fibres such as cotton, wool or bamboo, or natural filament suchas silk.

The yarns used to construct any component of the positioning andstabilising structure may be formed of a monofilament or a plurality ofsingle filaments, that is, a multifilament yarn.

The yarn may include separate filaments that are each formed ofdifferent materials. The yarn may also include filaments that are eachformed of two or more different materials, such as bicomponent yarn withfilaments having a sheath-core configuration or two halves formed ofdifferent materials. Different degrees of twist or crimping, as well asdifferent deniers, may affect the properties of the positioning andstabilising structure 3300.

The materials utilized to construct the positioning and stabilisingstructure components 2900 may be made recyclable or biodegradable, forexample, the yarns may include recyclable or biodegradable fibers orfilaments.

Areas of the positioning and stabilising structure 3300 subject togreater wear (for example but not limited to areas or regions cominginto contact with a patient's pillow), such as an area of positioningand stabilising structure 3300 located at the back of the head or napeof the neck, may possibly be more densely fabricated and may thus be aheavier weight and less extensible. Conversely, this area may be subjectto the greatest amount of moisture accumulation through sweat, andtherefore may need to be made of a thin, yet strong, net-likeconstruction with a custom aperture pattern. In this case, theabrasion-resistance may need to be inherent in the yarn properties only.

3D Printing

In another example, positioning and stabilising structure 3300 may bemanufactured to shape using a 3D printer. As shown in FIG. 143, a 3Dprinter may be used to print a plurality of connected links 2802 therebyforming a flexible 3D printed textile 2804. Referring to FIG. 144, apositioning and stabilising structure piece 2900 may be formed toinclude a rigidiser arm 3302. The rigidiser arm 3302 includes holes 2922through which the links of the textile 2804 may pass as the textile 2804is printed to integrate the textile 2804 and the rigidiser arm 3302. Therigidiser arm 3302 could be made from any suitable material (e.g., apolymer such as Nylon 12 or a sintered solid from a metal powder, or anyother material able to be used as an additive manufacture process). Asthe additive manufacture (“3D Printing” process technologies improve, itis envisioned that the material selection will become broader for thepurposes of 3D printing textiles, with the optional inclusion of a rigidcomponent such as the rigidiser arm 3302. Structure could be inherent inmaterial or by virtue of shape, form or structure.

Further, as shown in FIG. 145, a 3D printed strap 2924 may be integratedinto holes 2912(1), 2914(1) of male and female clips 2912, 2914.

Fashioning and Finishing the Strap

FIGS. 79 and 80 show views of the strap 3301 at an intermediate step ofproduction. The exemplary strap 3301 shown is a raw length of strap thathas not been cut to length from the knitted material produced, inexamples, by the methods and processes described above. For example, apair of button-holes 3303 can be seen at the left-most end of the strap3301, however, once finished only hole will be at that end because theraw strap will have been cut between those holes to produce the strapshown in FIG. 81. Also, the knitting process that forms the raw lengthof strap 3301 shown in FIG. 79 forms multiple split regions 3326 alongthe length of the strap. However, the finished strap 3301 shown in FIG.81 only includes one split region 3326. Again, this is because duringfinishing the strap 3301 will be cut between the right-most button-hole3303 shown in FIG. 79 to separate the raw length of strap 3301 shownthere into multiple straps.

According to one example of the technology, the strap 3301 may be formedusing a warp labelling machine with multiple bars to form chains in thefabric. According to another example, the strap 3301 may be formed by aComez machine with six bars for joining the two side strap portions3315, 3316 and the two back strap portions 3317 a, 3317 b in the center.By adding more bars to the Comez machine more directions of knitting maybe accommodated. The knitting process may also include forming the strap3301 with a different weave at the bifurcation point 3324. The materialof the strap 3301 may include a 1740 count. The order of pattern typesfor knitting a strap 3301 may be as follows: normal, then button-hole,then normal, then split, then normal, then button-hole, and then normal.A subsequent strap 3301 would then be knitted with this same order againgoing forward for each strap 3301 produced.

In one example of the present technology, the thread used for knittingthe strap 3301 may be double helically wound.

To add further strength at potential failure points, the strap 3301 maybe formed with extra stitching at these points. Potential failure pointsmay include the button-holes 3303, 3304 and the bifurcation points 3324.Also, additional threads may be knitted along the middle of the strap3301 for additional reinforcement.

FIG. 80 shows a cross-sectional view of the side strap portion 3316 ofFIG. 79 taken through line 80-80. A bifurcation point 3324 can be seento indicate the split region 3326 of the side strap portion 3316 and thedivision between the upper back strap portion 3317 a and the lower backstrap portion 3317 b.

FIG. 79 also indicates dimensions L₁-L₆ for the various features of thestrap 3301. L₁ indicates a distance between a button-hole 3303 of onestrap 3301 and a button-hole 3303 of an adjacent strap. In one exampleof the technology L₁ may be about 515 mm. L₂ indicates a distancebetween button-holes 3303 of the same strap 3301 and this value may,according to one example, be about 500 mm. L₃ indicates the length ofthe split region 3326 which may be about 200 mm in one example of thetechnology. L₄ may indicate the distance between adjacent button-holes3303 of adjacent straps 3301 and may be about 15 mm in one example. L₅may indicate the width of a button-hole 3303 and may be about 5 mm inone example. L₆ may indicate the width of the strap 3301 and may beabout 15 mm in one example.

FIGS. 81 to 83 show views of a finished strap 3301 according to anexample of the present technology. As can be seen in FIG. 81 there isonly one split region 3326 and only one button-hole 3303 at each end ofthe strap 3301. Therefore, it should be understood that this strap 3301has been cut and finished from the strap 3301 shown in FIG. 79,according to an example of the technology. Also, shown in FIG. 81 is astrap logo 3357 that may be formed on the strap 3301 in the form of acorporate logo or other artwork, for example. The strap logo 3357 may beformed by pad printing or ultrasonic welding. If the strap logo 3357 isformed by ultrasonic welding this may help to splay the back strapportions 3317 a, 3317 b at the bifurcation points 3324 to encouragespreading the back strap portions 3317 a, 3317 b by the patient 1000 toensure ideal fitment and strap tension.

FIG. 81 also shows end welds 3311.1, 3313.1. As described above, theside strap portion 3316 may be knitted into a hollow or tube-like shape.Thus, the ends will be open if not closed by welding, for example, whichprevents tearing along open ends. The end welds 3311.1, 3313.1 may beformed by ultrasonic welding to seal loose fibers of the strap 3301.While ultrasonic welding may reduce the stretchability of the fabricthat comprises the strap 3301 it may serve to reduce fraying at the endsand to add strength at high stress points. Since the end welds 3311.1,3313.1 are proximal to the respective pocketed ends 3311, 3313 the endwelds provide strength for the strap 3301 to be retained to therigidiser arms 3302 at their respective protruding ends 3306. It shouldbe understood that the pocketed ends 3311, 3313 and their respective endwelds 3311.1, 3313.1, according to one example of the technology, arethe primary portion of the strap 3301 for retention and/or anchoring tothe rigidiser arms 3302. The strap 3301 may lose elasticity afterprolonged use but it should be understood that by washing and drying thestrap 3301 at least some or all of this elasticity may be recovered.

The StretchWise™ headgear provided by Fisher & Paykel™ for the Pilairo™mask has a rigid detachable pivotal connection between rigid plastichooked ends of the headgear strap and rigid plastic vertical barslocated on the mask frame. In contrast, the strap 3301 of one example ofthe present technology does not have a rigid detachable connectionbetween the strap 3301 and the mask frame 3310 which avoids problemssuch as creep and breakage of hooked ends after repeated engagement anddisengagement of rigid components. A significant amount of force isrequired to materially deform the rigid hooked ends of the StretchWise™headgear to engage and disengage it from the rigid bars. In contrast,the rigidiser arms 3302 of the present technology are inserted intobutton-holes 3303 of the strap 3301 and retained in a pocketed end ofthe strap 3301 without such a significant force because no plasticdeformation of either the rigidiser arm 3302 or the strap 3301 isrequired to connect or disconnect the strap 3301 to and from the maskframe 3310. Another deficiency of the StretchWise™ headgear is thatelasticity of the headgear strap does not recover to substantially theoriginal level of elasticity after washing the headgear strap. In otherwords, the StretchWise™ headgear will become looser over time.

FIG. 82, similar to FIG. 80, shows a cross-sectional view of the strap3301 taken through line 83-83 of FIG. 81. The bifurcation point 3324 canbe seen that indicates the initiation of the split region 3326. Also,the strap logo 3357 can be seen raised from the side strap portion 3316in this view.

FIG. 83 shows a detailed view of the strap 3301 and particularly showsthe strap logo 3357. Also, the bifurcation point 3324 can be seen at thebeginning of the split region 3326.

FIG. 81 also shows additional dimensions that describe features of theexemplary strap 3301. L₇ may indicate the distance between the finishedend of the strap 3301 at the end weld 3311.1, 3313.1 and may be about 5mm in one example. L₈ may indicate the width of the end welds 3311.1,3313.1 and may be about 1 mm in one example.

Donning the Patient Interface and Positioning and Stabilising Structure

An exemplary patient interface 3000 and positioning and stabilisingstructure 3300 may be donned in a simple yet adjustable manner accordingto various examples of the present technology. As will be described ingreater detail below, FIGS. 84 to 112 depict various sequences of awearer (i.e., a patient) 1000 donning and adjusting the patientinterface 3000 and positioning and stabilising structure 3300.

FIGS. 84 to 88 show a series of perspective views of a patient 1000donning the patient interface 3000 and positioning and stabilisingstructure 3300. In FIG. 84 the patient 1000 begins donning the patientinterface 3000 and positioning and stabilising structure 3300 by holdingthe patient interface 3000 and placing the seal-forming structure 3100against the nose. FIG. 85 then shows the patient 1000 beginning to donthe positioning and stabilising structure 3300. The patient 1000 pullsthe strap 3301 near the split region 3326 with one hand while holdingthe patient interface 3000 with the other hand to stretch the strap 3301over the head. FIG. 86 then shows the patient 1000 pulling the strap3301, while still holding the split region 3326 with one hand and thepatient interface 3000 with the other, further towards the back of thehead. At the completion of this step the strap 3301 should be located atthe back of the head near the crown and near or above the occipital lobeso that proper tension sealing force is placed on the positioning andstabilising structure 3300 to hold the patient interface 3000 againstthe patient's 1000 nose. FIG. 87 then shows the patient 1000 adjustingthe positioning and stabilising structure 3300 to locate the rigidiserarms (not visible in these views) under the cheek bones and to adjustthe fit of the seal-forming structure 3100 against the nose to ensure acomplete seal. By locating the rigidiser arms 3302 under the cheek bonesthe positioning and stabilising structure 3300 may be prevented fromriding up on the face of the patient 1000 and into the patient's line ofsight. FIG. 88 then shows the patient 1000 with the patient interface3000 and positioning and stabilising structure 3300 donned and preparedfor therapy.

FIGS. 89 to 93 show a series of side views of a patient 1000 donning thepatient interface 3000 and positioning and stabilising structure 3300.FIG. 89 shows the patient 1000 holding the patient interface 3000 in onehand and raising it toward the nose while holding the strap 3301 of thepositioning and stabilising structure 3300 in the other hand. At thispoint the strap 3301 may not be significantly stretched. FIG. 90 showsthe patient 1000 locating the patient interface 3000 against the nose,particularly the seal-forming structure 3100, with one hand and pullingthe strap 3301 of the positioning and stabilising structure 3300 tostretch it over the head with the other hand. A separation at the splitregion 3326 can be seen as well due to the pulling of the strap 3301.FIG. 91 shows the patient 1000 still holding the seal-forming structure3100 and the patient interface 3000 against the nares while pulling thestrap 3301 of the positioning and stabilising structure 3300 furthertoward the back of the head. At this point, the initial step of donningthe patient interface 3000 and positioning and stabilising structure3300 should be nearly complete such that the strap 3301 is locatedagainst the back of the patient's 1000 head. FIG. 92 then shows thepatient 1000 adjusting the seal-forming structure 3100 and the patientinterface 3000 against the nose to ensure a proper seal and properlocation of the rigidiser arms 3302 relative to the cheek bones. FIG. 93then shows the patient 1000 with the patient interface 3000 andpositioning and stabilising structure 3300 donned and prepared fortherapy.

FIGS. 94 to 98 show a series of front views of a patient 1000 donningthe patient interface 3000 and positioning and stabilising structure3300. FIG. 94 shows the patient 1000 beginning to don the patientinterface 3000 and positioning and stabilising structure 3300. Holdingthe patient interface 3000 with one hand and the strap 3301 of thepositioning and stabilising structure 3300 with the other hand, thepatient 1000 raises the patient interface and positioning andstabilising structure toward the face. FIG. 95 shows the patient 1000with the positioning and stabilising structure 3300 in one hand and thestrap 3301 slightly stretched. FIG. 95 also shows the patient interface3000 held in the other hand and near the nose for placing theseal-forming structure 3100 against the nose. FIG. 96 shows the patient1000 having stretched and pulled the strap 3301 of the positioning andstabilising structure 3300 over the head and locating the strap 3301against the back of the head while holding the seal-forming structure3100 and the patient interface 3000 against the nose. FIG. 97 shows thepatient 1000 then adjusting the positioning and stabilising structure3300 and the patient interface 3000 by locating the rigidiser arms 3302in a comfortable position to seat under the cheek bones so that thepositioning and stabilising structure 3300 does not ride up into thepatient's line of sight and a seal can be maintained against the nareswith the seal-forming structure 3100. FIG. 98 then shows the patient1000 with the patient interface 3000 and positioning and stabilisingstructure 3300 donned and prepared for therapy.

FIGS. 99 to 104 show a series of perspective views of a patient 1000donning the patient interface 3000 and positioning and stabilisingstructure 3300. FIG. 99 shows the patient 1000 beginning to don thepatient interface 3000 and positioning and stabilising structure 3300 bystretching the strap 3301 while holding the strap 3301 with one hand andthe patient interface 3000 with the other hand. FIG. 100 then shows thepatient 1000 placing the patient interface 3000 and positioning andstabilising structure 3300 on the head by raising the patient interface3000 toward the face and pulling the strap 3301 over the back of thehead. FIG. 101 then shows the patient 1000 placing the seal-formingstructure 3100 against the nares with one hand while holding the strap3301 in a stretched state near the back of the head. FIG. 102 then showsthe patient 1000 locating the strap 3301 at the back of the head bybeginning to release its tension sealing force. The patient 1000, inFIG. 102, is still holding the patient interface 3000 against the noseto ensure that a proper seal is retained as tension sealing force isreleased from the strap 3301. FIG. 103 shows the patient 1000 adjustingthe patient interface 3000 against the nares to ensure a proper fit andseal as well as to locate the rigidiser arms under the cheek bones. FIG.104 then shows the patient 1000 with the patient interface 3000 andpositioning and stabilising structure 3300 donned and prepared fortherapy.

FIGS. 105 to 107 show perspective views of the patient 1000 adjustingthe patient interface 3000 against the nares to ensure a proper seal bythe seal-forming structure 3100. From FIG. 105 to FIG. 107 the patient1000 can be seen tilting the patient interface 3000 progressivelyfurther downward and against the nose to complete the seal against thenose with the seal-forming structure 3100. These views show the patient1000 adjusting the patient interface 3000 with one hand, although itshould be understood that the patient interface 3000 could be locatedand adjusted with two hands.

FIGS. 108 to 112 show a series of rear views of a patient 1000 adjustingthe positioning and stabilising structure 3300 against the back of thehead. FIG. 108 shows the positioning and stabilising structure 3300resting against back of the head. The strap 3301 will have its largestamount of tension sealing force in this position. FIG. 109 then showsthe patient 1000 grasping the upper back strap portion 3317 a with onehand and the lower back strap portion 3317 b with the other hand andpulling these back strap portions 3317 a, 3317 b apart at the splitregion 3326. It should be understood that by pulling these back strapportions 3317 a, 3317 b apart that the tension sealing force inpositioning and stabilising structure 3300 is decreasing from theposition shown in FIG. 108 because the back strap portions 3317 a, 3317b are becoming nearer to the patient interface 3000, which is resting ina constant position against the nares. By moving the back strap portions3317 a, 3317 b closer to the patient interface 3000, the stretchedlength of the strap 3301 is decreased thus decreasing its tensionsealing force. FIG. 110 is similar to FIG. 109, however in this view thepatient 1000 has pulled the upper back strap portion 3317 a and thelower back strap portion 3317 b further apart. It should be understoodthat the tension sealing force in the positioning and stabilisingstructure 3300 has decreased further due to the spreading of the backstrap portions 3317 a, 3317 b. FIG. 111 shows a further view of thepatient 1000 spreading the upper back strap portion 3317 a and the lowerback strap portion 3317 b apart. Tension sealing force will be decreasedagain from the position shown in FIG. 110. Also, at this point thepatient 1000 has nearly completed adjustment of the positioning andstabilising structure 3300 to the desired level of tension sealingforce. The upper back strap portion 3317 a may be located near the topof the head and the lower back strap portion 3317 b may be located nearor below the occipital lobe. FIG. 112 then shows the patient 1000 withthe positioning and stabilising structure 3300 fully adjusted to adesired level of tension sealing force. Again, the upper back strapportion 3317 a may be located near the top of the head and the lowerback strap portion 3317 b may be located near or below the occipitallobe. Furthermore, it should also be understood that as the tensionsealing force in the positioning and stabilising structure 3300decreases as the upper back strap portion 3317 a and the lower backstrap portion 3317 b are pulled apart, θ increases accordingly. Althoughnot indicated in these views θ may be about 0° in FIG. 108 and itincreases through the adjustment sequence. If θ has increased to amaximum of about 180° in FIG. 112, then the tension sealing force inpositioning and stabilising structure 3300 may be about 40% of thetension sealing force in FIG. 108. In another example of the presenttechnology, it may be possible to maintain angle θ at a predeterminedvalue at the initial point of bifurcation of the upper back strapportion 3317 a and lower back strap portion 3317 b, for example, if therigidiser arm 3302 extends to the bifurcation point 3324 and splits intoupper and lower arms both extending slightly into the back strapportions 3317 a, 3317 b. This may encourage the patient 1000 to splitthe back strap portions 3317 a, 3317 b to adjust headgear tension. Also,it reinforces the bifurcation point 3324, for example, using an externalseam tape or a plastic clip on the Y-shaped section where a side strapportion 3315, 3316 converges with the back strap portions 3317 a, 3317b. Such a plastic clip may provide a branding opportunity by padprinting branding and logo information on it.

In one form of the present technology, the positioning and stabilisingstructure 3300 has two points of connection with the frame 3310 andhence there are two rigidiser arms 3302 and a single hollow strap 3301with split region 3326. One problem with this type of patient interface3000 is that the split region 3326 may ride up or down depending onwhich back strap portion 3317 a, 3317 b has more pull. In order to thisproblem, the split region 3326 that contacts the back of the patient'shead has an even distribution in pull in either direction (top tobottom). Therefore the problem of riding up or down is alleviated.

The positioning and stabilising structure 3300 may comprise at least onestrap 3301 (see, e.g., FIG. 166) and at least one rigid element orrigidiser arm 3302 (see, e.g., FIG. 19). The strap may be made of anelastic material and may have elastic properties. In other words, thestrap 3301 may be elastically stretched, e.g., by a stretching forceand, upon release of the stretching force, returns or contracts to itsoriginal length. The strap 3301 may be made of or comprise anyelastomeric material such as elastane, TPE, silicone etc. The strapmaterial may also represent a combination of any of the above materialswith other materials. The strap 3301 may be a single layer or multilayerstrap. The sides of the strap 3301, particularly the sides forcontacting the patient during use, may be woven, knitted, braided,molded, extruded or otherwise formed. This may be achieved by the strap3301 being made of or comprising a layer of a material exhibiting therespective properties. The strap 3301 may comprise or is made of atextile material such as a woven material. Such material may compriseartificial or natural fibers for, on the one hand providing desired andbeneficial surface properties such as tactile properties. On the otherhand, the strap material may include elastomeric material for providingthe desired elastomeric properties.

In the FIGS. 65 to 145, the strap 3301 is shown as being one individualstrap for being attached, directly or via the frame 3310, to aseal-forming structure 3100. However, it may be appreciated that thestrap 3301 may comprise multiple individual straps which are or may beconnected to one another. Adjustment may be provided, however, byvarying where the strap is secured to a patient interface or other rigidelements such as a connector. In addition or alternatively, adjustmentcould be allowed by adding a mechanism, such as slide over ladder lockclips on the back or side straps (as shown, e.g., in FIGS. 75, 76 and166) or by otherwise adjusting the elastic length of the strap 3301 andpositioning and stabilising structure 3300, respectively.

Rigidiser Arm 3302

As can be seen in FIGS. 19 and 166, an example of the present technologymay comprise stiffened headgear to retain the patient interface 3000 onthe patient 1000. As shown in the drawings depicting this example, thepositioning and stabilising structure 3300 may contain at least onerigidiser arm 3302.

In the present example of the technology, the seal-forming structure3100 of the patient interface 3000 is retained in a desired position onthe underside of the nose of the patient 1000 by the support ofrigidiser arms 3302. The positioning and stabilising structure 3300 maylocate the patient interface 3000 such that it does not contact thepatient 1000 except at the seal-forming structure 3100.

In certain prior art examples the patient interface may be designed toat least partially rest against the upper lip of the patient and indoing so the face of the patient's upper lip provides a measure ofsupport to retain the patient interface in a desired location, asdescribed in U.S. Pat. No. 7,900,635. In the present example, however,it is desired that the patient interface 3000 not rest against the upperlip of the patient 1000, as can be seen in FIGS. 18 and 19.Particularly, FIG. 19 shows the posterior wall 3220 of the plenumchamber 3200 is shown separated from the septum and/or upper lip of thepatient 1000 by a gap or spacing S. This arrangement has the advantageof preventing irritation or injury to the patient 1000 at the septumand/or upper lip by contact and friction with the posterior wall 3220 ofthe plenum chamber 3200 during extended periods of wear. Avoidance ofconcentrated pressure on certain locations of the septum and/or theupper lip can prevent skin breakdown and sores from forming.

The arrangement of this particular example, wherein the patient's septumand/or upper lip is separated from the posterior wall 3220 of the plenumchamber 3200 is accomplished by rigidiser arm 3302, as can be seen inFIGS. 19 and 166. As shown in FIG. 19, the rigidiser arm 3302 of thepositioning and stabilising structure 3300 may be supported against thecheek of the patient 1000, approximately above the nasolabial sulcus(see FIG. 2c ). The rigidiser arm 3302 of the positioning andstabilising structure 3300 may be formed with a predetermined curve atthe curved profile 3323 to approximate the curve of the patient'scorresponding cheek region until the patient's cheekbone. The rigidiserarm 3302 may extend across a substantial portion of the cheek regionfrom the point of connection with the frame 3310 until the distal freeend 3302.1 of the rigidiser arm 3302. The distance between the point ofconnection with the frame 3310 until the distal free end 3302.1 of therigidiser arm 3301 is about 120 mm. Rigidiser arm 3302 may extend at anangle, e.g., approximately a right angle, away from the patient's faceand substantially parallel to the nasal ala. In other words, an innersurface of the main section 3333 of the rigidiser arm 3302, inparticular, the curved profile 3323 contacts and extends across asubstantial portion of the patient's cheek region. This contact resultsin the locating and locking the patient interface 3000 on the patient'sface at semi-fixed position. This contact minimises any verticalmovement of the rigidiser arms 3302 relative to the patient's face.Also, at least a region of the curved profile 3323 proximal to the sharpbend 3307 is intended to maintain contact with the patient's cheekboneor cheek. When the patient 1000 lies with one side of their face againsta bed pillow, the force exerted against the rigidiser arm 3302 and/orsome of the extension 3350 or flexible joint 3305 on the bed pillow isminimised or prevented from transmitting to the other rigidiser armbecause the sharp bend 3307 and extension 3350 of that rigidiser arm3302 largely absorb such a force before affecting the seal with thepatient's airways. In other words, lateral force acting upon thepositioning and stabilising structure 3300 is at least partiallydecoupled because the region of the curved profile 3323 is in contactwith the patient's cheek and there is some absorption of this force bythe extension 3350 or flexible joint 3305.

Rigidiser arm 3302 may also provide a supported decoupling of thepatient interface 3000, such that the patient interface 3000 may belocated in a desirable position at the underside of the patient's nosewith the tension forces of positioning and stabilising structure 3300retaining the patient interface 3000 in position not causing undesirablecontact of the patient interface 3000 against the septum and/or upperlip. Furthermore, the rigidiser arm 3302 may be dimensioned such thatthe posterior wall 3220 is distance from the patient's septum and/orupper lip by spacing S. Additionally, the tension of the positioning andstabilising structure 3300 is transmitted primarily to the patient'scheeks across the width and breadth of rigidiser arm 3302 and notagainst inwardly towards the face of the patient 1000 against the nose.This exemplary arrangement is advantageous because using the tissue ofthe cheeks, a relatively large region of the face, to dissipateretention forces may afford the patient greater comfort, as opposed tousing the patient's nose and/or upper lip, which may be more sensitivedue to its cartilaginous nature. This exemplary arrangement also allowsthe seal-forming structure 3100 to be retained with an amount of forcesufficient to create a seal against the patient's airways at theunderside of the patient's nose, while not allowing the retention forceto rise to the level of causing discomfort to the patient 1000.

It may be desirable to avoid contact between the rigidiser arms 3302 andthe plenum chamber 3200. Thus, the plenum chamber 3200 may be madesufficiently wide so as to avoid contact with the rigidiser arms 3302.

Stretching of Headgear Strap Relative to Rigidiser Arm

In the example shown in FIG. 166, two rigidiser arms 3302 are insertedinto right and left side strap portions 3315, 3316 of the strap 3301 ofthe positioning and stabilising structure 3300, the rigidiser arm 3302is held in place by the surrounding strap 3301 while at the same time asleeve-like configuration of strap 3301 allows at least a portion of thestrap to stretch or move relative to the rigidiser. The rigidiser arm3302 cannot be seen in this view as it is contained within the strap3301.

The attachment of the strap 3301 to the rigidiser arm 3302 described inthe preceding section may also effect the size of head that thepositioning and stabilising structure 3300 may accommodate. In otherwords, by providing a greater length of strap 3301 along the rigidiserarm 3302 it may be possible to increase the total stretchable length ofthe positioning and stabilising structure 3300 such that even largerheads may be accommodated without needing to increase the stretchabilityof the strap. Furthermore, it may be possible to vary, along the lengthof the rigidiser 3302, where the strap 3301 is connected. This wouldallow for an even greater range of head sizes to be accommodated without

The rigidiser arm 3302 may thus be allowed to move generallyunrestrictedly along the length of the sleeve, attached to the sleeve3301, or may be adjacent to one of its ends.

Split Back Straps of Positioning and Stabilising Structure

According to one aspect, the structure of strap 3301 and positioning andstabilising structure 3300 is of advantage. In particular, as FIG. 166depicts, the provision of two elastic straps or strap portions 3317 a,3317 b at the back allows the head to be cupped and the tensionvector(s) to be adjusted by suitably positioning them, e.g. byspreading. The provision of two back strap portions 3317 a and 3317 balso allows better support and stability, as well as increasedflexibility in avoiding specifically sensitive regions of the back ofthe head.

The two smaller straps or strap portions 3317 a, 3317 b at the back ofthe head may be equal in length and not adjustable except through theelasticity of the material or through increasing both in tightnessequally by shortening the total length at the arms of the positioningand stabilising structure. For example, a sliding mechanism (not shown)may be provided that allows the straps to be overlapped to a differentextent, thus changing the overall length of the positioning andstabilising structure 3300.

As indicated above, two or more joints could be provided creating thepositioning and stabilising structure 3300 from three, four or moreseparate straps rather than strap 3301 being one continuous piece. Thismight complicate the assembly, but may simplify the manufacturingprocess. Joints may be placed at the bifurcation or Y-junction betweenthe side strap portions 3315, 3316 and two back strap portions 3317 a,3317 b or cantered at the back. The joints may be sewn, welded, glued,or over molded and could incorporate a high friction material to helpreduce movement on the head.

In one example of the present technology, one or more threads of thestrap 3301 may consist of an adhesive or glue. After the strap 3301 ismanufactured with this thread, heat is applied to the strap 3301 causingthe adhesive or glue thread to melt to reinforce the strap 3301 in areasat or proximal to the adhesive or glue thread.

High friction materials may also be added to the inside surface of theback and side strap portions 3315, 3316, 3317 a, 3317 b, to reduce thestraps slipping. For the arms or side strap portions 3315, 3316 thiswould help the positioning and stabilising structure 3300 stay on thecheeks and at the back strap portion 3317 it could stop the positioningand stabilising structure 3300 from sliding across the back of the head.Such material may be printed, cast or molded onto the surface orincorporated into joints, sewing or welding processes as mentionedabove.

The split region 3326 at the back of the patient's head may include two,three or more straps 3317 a, 3317 b for stability. A positioning andstabilising structure 3300 similar to the described, may be used withfull face (one or more seals for the nose and mouth) or nasal masksalso.

It is possible that the maximum distance permitted between the backstrap portions 3317 a, 3317 b may be limited or constrained to preventthe back strap portions 3317 a, 3317 b being split apart completely orsplit beyond a predetermined distance. A joining strap across the splitregion 3326 or netting across the split region 3326 may be connected tothe back strap portions 3317 a, 3317 b to limit their ability to splitapart beyond a predetermined distance.

The Connection Between a Mask Frame and a Rigidiser Arm

According to examples of the present technology to be described ingreater detail below in reference to FIGS. 35 to 64, the patientinterface 1000 may include a mask frame 3310 and a rigidiser arm 3302.As will become apparent from the following description the rigidiser arm3302 may function to direct the vector of tension generated by a strap3301 or straps of the positioning and stabilising structure 3300 in adesired direction so as to ensure effective sealing of the seal-formingstructure 3100 against the patient's airways, while directing straps3301 of the positioning and stabilising structure 3300 away from thepatient's eyes and line of sight. Thus, it should also be understoodthat the rigidiser arm 3302 and the mask frame 3310 must be formed andconnected to facilitate an effective direction of the sealing force. Itmay be advantageous to allow the rigidiser arm 3302 to flex relative tothe mask frame 3310 to accommodate the various shapes and sizes ofpatients' faces and heads. To improve patient comfort, the direction anddegree of flexing between the rigidiser arm 3302 and the mask frame 3310may be specifically controlled. A flexible joint 3305 may accomplishthis or the rigidiser arm 3302 may be directly connected to the maskframe 3310.

A Flexible Joint to Connect a Rigidiser Arm and a Mask Frame

Referring to FIGS. 35 to 38, a patient interface 3000 is providedgenerally comprising a mask frame 3310, a rigidiser arm 3302 and aflexible joint 3305. A retaining structure 3242 may be removablydetachable with the mask frame 3310. The retaining structure 3242 mayhold a seal-forming structure 3100 on the mask frame 3310. The rigidiserarm 3302 may be made from a thermoset or thermoplastic. For example,Hytrel® 5556 manufactured by DuPont™ is a thermoplastic polyesterelastomer which exhibits excellent creep resistance and may be used asthe material for the rigidiser arm 3302. The rigidiser arm 3302 may bepart of a positioning and stabilising structure 3300 to locate andretain the mask frame 3310 in position on a patient's face for deliveryof respiratory therapy. In one example, the positioning and stabilisingstructure 3300 has two rigidiser arms 3302 at its distal ends. Eachrigidiser arm 3302 may be permanently connected to opposite sides of themask frame 3310.

An elastic fabric strap 3301 may be slipped over each rigidiser arm 3302to form the positioning and stabilising structure 3300 as disclosed, forexample, in U.S. Provisional Application No. 61/676,456, filed Jul. 27,2012, which is incorporated by reference herein in its entirety. Theelastic fabric strap 3301 may extend around the head of the patient 1000and may be bifurcated to provide self-adjustment. The rigidiser arm 3302may also include a protruding end 3306 that retains a pocketed end ofthe elastic fabric strap 3301. In an example, the rigidiser arm 3302 isinserted through a button-hole proximal to the pocketed end and into thehollow elastic fabric strap 3301. When the elastic fabric strap 3301 isstretched as the patient interface 3000 is donned, the direction ofstretch and headgear tension vector of the elastic fabric strap 3301 isguided by the shape and profile of the rigidiser arm 3302. Theprotruding end 3306 is a fixed anchor at the base of the rigidiser arm3302 proximal to the mask frame 3310 and provides the starting point forthe stretch of the elastic fabric strap 3301. The protruding end 3306permits the elastic fabric strap 3301 to be connected and disconnectedfrom the rigidiser arm 3302 to facilitate washing of the elastic fabricstrap 3301 separately from the mask frame 3310 and rigidiser arms 3302.The rigidiser arm 3302 also frames the face by keeping the elasticfabric strap 3301 away from the eyes and over the ears which leads tothe patient interface 3000 being perceived as unobtrusive by thepatient. The rigidiser arm 3302 may be generally a planar arm of apredetermined thickness. The thickness of the rigidiser arm 3302 mayvary along its length and may be about 1 mm at a distal free end 3302.1and gradually increases in thickness to 1.5 mm along the curved profile3323 until the distal portion of the rigidiser arm 3302 proximal to thepoint of connection with the flexible joint 3305. Since the distal freeend 3302.1 has less material relative to the other areas of therigidiser arm 3302 there is a tendency for any flexing of the rigidiserarm 3302 to occur on or proximal to the distal free end 3302.1 firstbefore other areas of the rigidiser arm 3302 start to flex. The order offlexing is intended to improve comfort because the distal free end3302.1 is close to the patient's ears, cheekbones and temples which canbe a particularly sensitive region of the face and conformity and lessresistance to bending and deformation may be required. A sharp bend 3307may be provided at a distal portion of the rigidiser arm 3302 proximalto the point of connection with the flexible joint 3305. The sharp bend3307 may be at an angle of substantially 90 degrees or less. The sharpbend 3307 may also provide increased rigidity to fix the rigidiser arm3302 in position relative to the mask frame 3310. The sharp bend 3307may prevent or minimise stretching in a longitudinal direction. Also,the sharp bend 3307 may accommodate compression of the rigidiser arm3302. If a force is applied to the side of a rigidiser arm 3302 in thecoronal plane, the majority of the flexing may occur at or proximal tothe sharp bend 3307.

The flexible joint 3305 may be provided between the rigidiser arm 3302and the mask frame 3310. The flexible joint 3305 may be made fromthermoplastic elastomer (TPE) which provides high elastic properties.For example, a Dynaflex™ TPE compound or Medalist® MD-115 may be used.The mask frame 3310 may be made from polypropylene (PP) material. PP isa thermoplastic polymer with good resistance to fatigue. An advantage ofthe flexible joint 3305 may be that it enables the rigidiser arm 3302and the mask frame 3310 to be permanently connected to each other.Hytrel® and PP cannot be integrally bonded to each other by formingcovalent or hydrogen bonds. Integrally bonded includes chemically bondedbut without the use of an added adhesive substance. In an example, therigidiser arm 3302 is provided with a protrusion 3309 that extendsoutwardly from the distal portion of the rigidiser arm 3302. Turning toFIG. 38, the inner side 3318 of the protrusion 3309 is the surface ofthe rigidiser arm 3302 that the protrusion 3309 extends from. An outerexposed side 3319 of the protrusion 3309 is opposite the inner side 3318(see FIG. 38). The protrusion 3309 may have a void 3320 in a centralregion of the protrusion 3309. The void 3320 may extend substantiallyvertically through the protrusion 3309 from a top side 3321 to a bottomside 3322 of the protrusion 3309, and may be enclosed around itsperimeter by the protrusion 3309. The outer side 3319 may be asubstantially planar surface that extends beyond the protrusion 3309.When viewed from above, the protrusion 3309 may have a generallyT-shaped cross section with the void 3320 visible in the central region.The protrusion 3309 may also serve to retain the elastic fabric strapalternatively or in addition to the protruding end 3306.

Another advantage of the flexible joint 3305 may be that it isrelatively more flexible than the rigidiser arm 3302. This flexibilitymay be provided by the combination of the TPE material and also thestructural features of the flexible joint 3305. Structurally, theflexible joint 3305 may have a predetermined thickness to enable apredetermined degree of flexing, and also the amount of curvature of theflexible joint 3305 may be selected to contribute to the degree offlexing. The flexible joint 3305 may be able to flex radially on itslongitudinal axis relative to the mask frame 3310 but may be resistantto flexing in other directions. This flexibility may provide aself-adjustment function to the patient interface 3000 and maycompensate for deviations to facial contours, nose dips or sleepingpositions. This flexing may accommodate the anthropometric range of mostpatients. Greater flexibility may be required at this location comparedto the flexibility within the rigidiser arm 3302 itself. Also, sinceflexing is restricted to a certain direction, stability of the maskframe 3310 may be improved and the position of the mask frame 3310 maybe substantially maintained relative to the nose and mouth if theelastic fabric of the positioning and stabilising structure 3300requires adjustment.

The flexible joint 3305 may be overmolded to the mask frame 3310. PP andTPE can be integrally bonded to each other. In other words, a fusionbond or chemical bond (molecular adhesion) between the flexible joint3305 and the mask frame 3310 is possible. This may form a permanentconnection between the flexible joint 3305 and mask frame 3310. Theflexible joint 3305 may be overmolded to the protrusion 3309 of therigidiser arm 3302. TPE and Hytrel® cannot be integrally bonded to eachother. However, during overmolding in accordance with an example of thepresent technology, the TPE material for the flexible joint 3305 flowsinto the void 3320 of the protrusion 3309 and around the protrusion3309. TPE material surrounds the front and rear sides and the top andbottom sides 3321, 3322 of the protrusion 3309. Consequently, amechanical interlock may be provided to form a permanent connectionbetween the flexible joint 3305 and the rigidiser arm 3302.

The outer side 3319 of the protrusion 3309 may be flush with the outersurface of the flexible joint 3305. This is visually aestheticallypleasing.

Referring to FIGS. 42 to 46, in another example, at the distal end ofthe rigidiser arm 3302 may be an extension 3350. The extension 3350 mayproject from the outer surface of the rigidiser arm 3302 via a stem3361. The extension 3350 may be L-shaped when viewed from above. Theextension 3350 may have a sharp bend 3307 of approximately 90 degreeswhich separates a first section 3363 from a second section 3364 of theextension 3350. The first section 3363 may be oriented in a plane thatis parallel to the outer surface of the rigidiser arm 3302 at the distalend. The end 3363A of the first section 3363 may have curved corners.The second section 3364 may have a height and thickness that is lessthan the first section 3363. Therefore the top and bottom edges of thesecond section 3364 may be set back from the top and bottom edges of thefirst section 3363. The rigidiser arm 3302 may also include a protrudingend 3306 that retains a pocketed end 3311 of the elastic fabric strap3301. The stem 3361 may also serve to retain the elastic fabric strapalternatively or in addition to the protruding end 3306.

The second section 3364 may have a first protrusion 3365 and a secondprotrusion 3366. The protrusions 3365, 3366 may extend laterally in anoutwardly direction from the rigidiser arm 3302. Adjacent to the firstprotrusion 3365 may be a first slot 3367 and adjacent to the secondprotrusion 3366 may be a second slot 3368. The slots 3367, 3368 each mayprovide a void through the thickness of the second section 3364 and mayhave approximately the same height as the protrusions 3365, 3366.

A flexible joint 3305 made from TPE may be overmolded to the secondsection 3364 of the extension 3350 of the rigidiser arm 3302. Duringovermolding, TPE material may flow through the slots 3367, 3368 andsurround the protrusions 3365, 3366. The majority of the second section3364 may be enclosed by the TPE material of the flexible joint 3305.This may provide a mechanical interlock which enables the flexible joint3305 to be permanently connected to the rigidiser arm 3302. Since thesecond section 3364 may have a height and thickness that is less thanthe first section 3363, the TPE material overmolded to the secondsection 3364 may not excessively protrude beyond the first section 3363.The flexible joint 3305 may also be overmolded to the mask frame 3310 toconnect the flexible joint 3305 and the rigidiser arm 3302 thereto.

Similar to the previously described example, greater relativeflexibility may be provided by the flexible joint 3305 relative to therigidiser arm 3302. Flexing in this location and the control of thedirection of flexing, may accommodate the anthropometric range of mostpatients and maintains stability of the patient interface 3000 in use.

A Direct Connection Between a Rigidiser Arm and a Mask Frame

Referring to FIGS. 39 to 41, in another example, a flexible joint 3305made from TPE may not be required. An extension 3350 may be used. Therigidiser arm 3302 may have a main body or main section 3333 comprisingthe curved profile 3323 and sharp bend 3307. The rigidiser arm 3302 mayalso include a protruding end 3306 that retains a pocketed end of theelastic fabric strap. Along a majority of its longitudinal axis, acurved profile 3323 may be shaped to correspond to an obtuse angle toclosely follow the contour of the face of a patient. At the distal endof the rigidiser arm 3302, an extension 3350 may be provided after thesharp bend 3307. The extension 3350 may project outwardly from therigidiser arm 3302 in the coronal plane. A recess 3329 (see FIGS. 40,50, 57, 58) may be defined in a surface of the rigidiser arm 3302 at thepoint the extension 3350 projects from the rigidiser arm 3302. Theheight of the extension 3350 may be less than the height of the mainsection 3333 of the rigidiser arm 3302. This may enable greaterflexibility for the extension 3350 compared to the main section 3333 ofthe rigidiser arm 3302 because of a relative reduction of material forthe extension 3350 relative to the rigidiser arm 3302. The rigidiser arm3302 including the extension 3350 may be made from Hytrel®. Hytrel®provides the rigidiser arm 3302 with a flexural modulus of 180 MPa at23° C. and a tensile modulus of 180 MPa (26). The enclosable section3354 of the extension 3350 may be overmolded by the PP material of themask frame 3310 at the edge of the mask frame 3310. This is performedin-mold and during overmolding, the PP material of the mask frame 3310may surround the inner, outer, top and bottom surfaces of the enclosablesection 3354 to permanently connect the rigidiser arm 3302 with the maskframe 3310 via a mechanical interlock. The encapsulation of theenclosable section 3354 of the extension 3350 by the PP material of themask frame 3310 provides a mechanical retention without an integral bondbetween the rigidiser arm 3302 and the mask frame 3310.

The connection between the rigidiser arm 3302 and the mask frame 3310 isa hinged connection at or proximal to bend 3352. In other words, therigidiser arm 3302 is able to pivot relative to the mask frame 3310. Theposition of the pivot point as far forward as possible in line with thenasal pillows and nares of the patient 1000 to cater for varying nosedroop and minimize the moment arm and tube drag caused by the aircircuit 4170. The flexing and rotational movement of the rigidiser arm3302 relative to the mask frame 3310 in the coronal plane is toaccommodate various head widths without excessive force, preferably,less than 1 or 2 Newtons, required to minimise or eliminate pinching ofthe patient's cheeks between the two rigidiser arms 3302. The distancebetween the two bends 3352 is about 62 mm. This spacing between thebetween the two bends 3352 avoids the protruding end 3306 of therigidiser arms 3302 and extension 3350 or flexible joint 3305 touchingthe patient's nose proximal to the nose tip and side of the patient'snose. These areas of the patient's face may be particularly sensitive soavoidance of contact in these areas may improve comfort.

As the patient interface 3000 is donned, the rigidiser arms 3302 may bespread outwardly to accommodate various head widths. Pivoting of therigidiser arm 3302 relative to the mask frame 3310 will occur as well asflexing of the rigidiser arm 3302 along its longitudinal axis.

Additional Features and Examples of the Present Technology

In another example the rigidiser arm 3302 may be relatively moreresiliently flexible than the mask frame 3310. The rigidiser arm 3302may also be formed so as to be flexible only horizontally, i.e., in aplane parallel to the Frankfort horizontal and the transverse plane.Moreover, the rigidiser arm 3302 may not be flexible in a verticaldirection, i.e., in a plane perpendicular to the Frankfort horizontal.In other words, the rigidiser arm 3302 is more flexible in a planeparallel to the Frankfort horizontal and the transverse plane and lessflexible in any other plane (preferably, not flexible). Furthermore,material of the rigidiser arm 3302 may not be stretchable or extensible.If the rigidiser arm 3302 is stretched at its ends, the curved profileof the rigidiser arm 3302 flattens. These features alone or incombination with shape and dimension may allow the rigidiser arm 3302 toflex and/or frame the face of the patient 1000 without riding or flexingup across or down against the patient's ears. In turn, this enables theelastic fabric strap 3001 to navigate above the patient's ears proximalto the Otobasion superior.

In the example shown in FIGS. 35 to 38, indicia such as a corporate logomay be provided on the outer surface 3319 of the protrusion 3309 toconceal the location of the mechanical interlock. In the example shownin FIGS. 39 to 41, the indicia may be provided on an outer surface 3355of the extension 3350. The indicia may visually assist the patient indetermining the correct orientation of the patient interface 3000 whendonning the patient interface 3000, to prevent it from being donnedupside down. If the indicia is also a raised/embossed surface, this mayprovide tactile feedback for the patient 1000 especially if they aredonning the patient interface 3000 in a darkened environment.

In a further example, an adhesive accelerator may be used after surfacetreatment to permanently connect the rigidiser arm 3302 to the maskframe 3310, or to permanently connect the rigidiser arm to the flexiblejoint 3305. In this example, a mechanical interlock is not necessary.

In another example, the rigidiser arm 3302 is made from a material thatcan be integrally bonded with the mask frame 3310 made from PP material.The rigidiser arm 3302 may be made from a fiber reinforced composite PPmaterial, for example, Curv® manufactured by Propex Inc. Curv® has asimilar level of resilient flexibility as Hytrel®. Curv® is provided insheet form, and requires laser cutting into the desired shape of therigidiser arm 3302. To obtain the desired thickness for the rigidiserarm 3302, compression or layering of sheets may be performed to adjustthe thickness of the rigidiser arm 3302 in certain areas. Since Curv® ismade from the same material as the mask frame 3310, an integral bond ispossible when the rigidiser arm 3302 is overmolded to the mask frame3310.

The patient interface 3000 may include nasal pillows or a nasal cradleas disclosed, for example, in U.S. Provisional Application No.61/823,192, filed May 14, 2013, which is incorporated herein byreference in its entirety. Nasal pillows may be releasably engageablewith the mask frame 3310. After the rigidiser arms 3302 are permanentlyconnected to the mask frame 3310, the elastic fabric strap of thepositioning and stabilising structure 3300 may be slipped over therigidiser arms 3302 and secured to the rigidiser arms 3302.

Although a T-shaped protrusion 3309 has been described, it is envisagedother shapes and forms are possible, including a mushroom shapedprotrusion, to permanently connect the rigidiser arm 3302 (via aflexible joint in one example) mechanically to the mask frame 3310.Although a void 3320 has been described, it is envisaged that theprotrusion 3309 may not have a void but rather recesses or slots toretain the flexible joint 3305 or mask frame 3310 to the rigidiser arm3302.

It is envisaged that it is possible to reverse the described connectionarrangement and provide the protrusion extending from the mask frame3310 or flexible joint 3305 rather than rigidiser arm 3302. In such anexample the rigidiser arm 3302 would be overmolded to the flexible joint3305 or the mask frame 3310.

It is envisaged that the flexible joint 3305 can be permanentlyconnected to the mask frame 3310 without an integral bond. For example,a mechanical interlock may be provided to permanently connect theflexible joint 3305 to the mask frame 3310.

Although the rigidiser arm 3302, flexible joint 3305 and mask frame 3310have been described as permanently connected to each other, it isenvisaged that some or all may releasably detachable from each otherusing for example, a mechanical clip (snap-fit) assembly.

The Shape of a Rigidiser Arm

FIGS. 61 to 64 show a rigidiser arm 3302 according to an example of thepresent technology plotted in two and three dimensions.

FIGS. 61 to 63 show three two dimensional views of a rigidiser arm 3302according to an example of the present technology plotted on a grid.FIG. 61 shows the X-Y plane, FIG. 62 shows the X-Z plane, and FIG. 63shows the Y-Z plane. The origin is also indicated in these views fororientation purposes. Numbered coordinates are also shown in each ofthese and these coordinates may define the curve of the rigidiser arm3302 in these planes. The following chart lists the coordinates of theprofile of the rigidiser arm 3302 shown in these views. It should beunderstood that each coordinate is numbered consistently across each ofthe four views.

Point # X Y Z 1 26.67 14.25 12.76 2 22.00 26.87 24.92 3 27.30 28.5726.37 4 37.94 32.84 30.10 5 46.72 37.84 34.57 6 59.77 51.55 45.79 765.02 61.69 52.45 8 68.36 73.68 56.36 9 69.09 83.53 55.98 10 69.78 94.7054.31 11 69.06 102.83 54.02 12 68.69 110.47 55.36 13 72.25 113.84 51.6514 73.00 110.04 49.69 15 73.70 103.72 48.28 16 73.81 95.03 48.56 1773.26 86.38 49.37 18 71.54 75.71 48.65 19 67.84 66.29 44.75 20 60.5555.68 36.66 21 52.68 48.30 29.33 22 43.87 42.88 23.34 23 33.65 38.8718.62 24 27.58 37.35 16.76 25 21.65 36.15 15.26 26 26.67 22.22 2.56

FIG. 64 shows a further view of the rigidiser arm 3302 depicted in FIGS.61 to 63 in three dimensions. The X, Y, and Z axes are indicated, aswell as the origin, to aid in orientation.

The shape of the curve of the rigidiser arm 3302 is intended to closelyfollow the patient's cheek. With the elastic fabric strap 1200 coveringthe rigidiser arm 3302, the relative position of the rigidiser arm 3302in contact with the patient's cheek during use is such that it does notslip on the patient's face. For example, the rigidiser arm 3302 may sitslightly below the patient's cheekbone which prevents the rigidiser arm3302 from sliding upwards. Also, contact between most of or all theinner side surface of the rigidiser arm 3302 and the patient's face mayincrease friction to prevent slippage and ultimately minimise disruptionof sealing forces. The shape of the curved profile 3323 of the rigidiserarm 3302 directs the positioning and stabilising structure 3300 betweenthe eyes and ears over the majority of the anthropometric range. Thisorientation is advantageous because it is aesthetic and unobtrusive fromthe perspective of the patient 1000 and the patient's bed partner 1100.When viewed from above, the curved profile 3323 of the rigidiser arm3302 has a larger radius than the rigidiser arm 3302 when viewed fromthe side.

The Flexibility of a Rigidiser Arm

As described earlier and referring to FIGS. 52 and 55, the rigidiser arm3302 is more flexible in certain directions at certain locations alongthe rigidiser arm 3302. Flexural stiffness of the rigidiser arm 3302 iscompared. For comparative purposes, the flexibility of the rigidiser arm3302 is measured against rigidised headgear of some prior masks byResMed Limited in an outwardly lateral direction in the coronal planeand in the inferior vertical direction in the sagittal plane.

Newtons of force (N) required to displace upper distal tip of rigidiserarm by 5 mm Laterally Mask name Mask type Vertical Down Outwards PresentTechnology nasal pillows 0.132 0.0143 ResMed Pixi paediatric nasal 1.1070.0356 ResMed Mirage Swift nasal pillows 1.15 0.0258 LT ResMed MirageSwift I nasal pillows 0.966 0.0647 ResMed Mirage Vista nasal 4.35 0.0776

This comparison shows the differences in force (in Newtons) required todisplace the upper distal tip of a rigidised headgear component whenconnected to a mask frame by a distance of 5 mm. Choosing the upperdistal tip of a rigidised headgear component as the location to measureis because this location comes into contact with a sensitive facial areaand certain types of flexibility provides comfort without compromisingseal stability. Measuring the direction of flexibility in an outwardlylateral direction in the coronal plane (laterally outwards) is intendedto measure the ability of the rigidiser arm 3302 to accommodate patientswith large face widths as shown in FIG. 52 in broken line. The resilientflexibility of the rigidiser arm 3302 allows the patient interface 3000to more precisely fit a wider range of facial shapes. For example, thesame patient interface 3000 could be used on patients with a narrowangular face (the so-called crocodile shape) as those with a widerflatter face (the so-called panda shape). Measuring the direction offlexibility in the inferior vertical direction in the sagittal plane(vertical down) is intended to measure the ability of the rigidiser arm3302 to handle tube torque exerted by the air circuit 4170 duringtherapy as shown in FIG. 55 in broken line. Both measurements are takenusing an Instron machine with a 50N load cell.

For measuring the vertical down direction, each mask is secured to aplate and sits level with it and has the rigidised headgear component atan angle that would be normally be on a patient's face. This plate isfastened to a large circular base plate used for the Instron machine.The rigidised headgear component is held in a jig to prevent twistingand slipping and this jig is manually lowered such that it makes contactwith the upper distal tip of the rigidised headgear component. TheInstron machine is zeroed at this height position. Next, compressionextension of 5 mm is applied at a rate of 50 mm/minute, and themeasurements are recorded.

For measuring the laterally outwards direction, a spacer and a 90 degreeelbow are secured to a first plate. Each mask is secured to a secondplate and sits level with it and has the rigidised headgear component atan angle that would be normally be on a patient's face. A spring clampis used to fix the second plate with the 90 degree elbow on the firstplate such that the first plate is held perpendicular to the secondplate. A large prong is used to locate it to the upper distal tip of therigidised headgear component. The Instron machine is zeroed at thisheight position. Next, compression extension of 5 mm is applied at arate of 50 mm/minute, and the measurements are recorded.

The measurements show that the rigidiser arm 3302 connected to the frame3310 is more flexible in both directions by a significant factor. Foraccommodating large face widths, the rigidiser arm 3302 is 1.8 timesmore flexible than the second most flexible mask in this direction(ResMed Mirage Swift LT). For accommodating tube torque, the rigidiserarm 3302 connected to the frame 3310, the rigidiser arm 3302 is 8.39times more flexible than the second most flexible mask in this direction(ResMed Pixi). By having a more flexible rigidiser arm 3302 whendisplaced in these directions provides the patient 1000 with greatercomfort, less likelihood of seal disruption caused by tube torque andtherefore leads to increased patient compliance with therapy in terms offrequency of use and therapy duration.

Relative flexibility of the rigidiser arm 3302 in different directionsis also an important consideration. If flexibility in the vertical downdirection is too high (i.e. equal to the laterally out direction), theremay be seal instability. In one example, the rigidiser arm 3302 is moreflexible in the laterally out direction than the vertical downdirection. The rigidiser arm 3302 is 9 to 10 times more flexible in thelaterally out direction than the vertical down direction. Preferably,the rigidiser arm 3302 is about 9.23 times more flexible in thelaterally out direction than the vertical down direction. Tube torquemay also be addressed in conjunction with other mask components such hasthe short tube 4180 (e.g. making it lighter weight, more slinky or moreflexible) or the use of a swivel connector, ball and socket joint orgusset or pleated section. However, varied facial widths arepredominantly addressed by the flexibility of the rigidiser arm 3302 andtherefore the rigidiser arm 3302 needs to be more flexible in thelaterally out direction compared to the vertical down direction.

Some rigidised headgear components of prior masks are more rigid thanthe frame. Typically, these stiff headgear components use threaded armsand bolts to manually adjust the headgear to fit the patient's head.Although a flexible frame may improve mask comfort, provide a good seal,minimise inadvertent leak and minimise the risk that headgear straps aretoo tight for low pressure level for therapy, some difficulty wouldarise if the flexible frame was needed to be releasably detachable witha seal-forming structure. Seal-forming structures are resilientlyflexible so that they form a seal against the patient's airways. If boththe seal-forming structure and frame are of similar flexibility (i.e.very flexible or floppy), it would be difficult for a patient 1000 toengage these two parts together, especially a patient with arthritichands in a darkened room.

Some rigidised headgear components of prior masks are detachable fromthe frame. Typically this is by way of a snap-fit or clip connectionbetween the rigidiser arm and the mask frame, both of which are rigidand stiff components. This type of hard-to-hard connection between therigidiser arm and frame may result in less flexibility at the point ofconnection which means more force is required to flex at this pointcausing discomfort for patients with larger face widths since a pinchingforce may be experienced when the rigidiser arms are forced to flexoutwardly. Some of these rigidiser headgear components have the hardclip at the distal end of the rigidiser arm for releasable connectionwith the frame. The hard clip is permanently connected to a headgearstrap which may damage a washing machine tub or other laundry items whenthe headgear is washed in a washing machine. Also, some of theserigidised headgear components tend to require a patient interface with awider frame which means that the headgear straps commence from the frameposition at a larger distance apart from other. The wider frame may haveintegrally formed lateral arms which are considered part of the frame asthey are made from the same material. A wider frame may be perceived bypatients 1000 and their bed partners 1110 as more obtrusive andaesthetically undesirable because they cover a larger footprint on theface. In contrast, in one example of the present technology, therigidiser arm 3302 is made from a material that is more flexible thanthe frame 33310 but less flexible than the strap 1200. In other words,the strap 1200 is the most flexible component of the positioning andstabilising structure 3300 as it is made from an elastic fabric. Thesecond most flexible component of the positioning and stabilisingstructure 3300 is the rigidiser arm 3302 which is made from Hytrel® inone example. The most rigid or stiff component is the frame 3310 whichnot intended to flex, stretch or bend easily or at all because it is theseal-forming structure 3100 that is meant to form a seal with thepatient's airways by resilient deformation. The differences inflexibility of individual components can control the amount of flexingat certain locations and also determine the order that certaincomponents start to flex when a certain force is applied i.e. tubetorque or accommodating a larger face width. The differences inflexibility of individual components may also decouple forces beforethey can begin to disrupt the seal of the seal-forming structure 3100 ina specific manner or sequence. These factors aim to address therequirements of comfort, stability and provision of a good seal at thesame time for a patient interface 3000. Another advantage of therigidiser arm 3302 is that the same sized rigidiser arm 3302 may be usedfor patient interfaces 3000 with different sized seal-forming structures3100 or different sized headgear straps 3301. When a rigidiser arm 3302is flexed inwardly, it is likely to make contact with the sides ofpatient's nose first before the making contact with the nasal pillows3130 and dislodging the seal. Then inward range of movement of therigidiser arms 3302 is limited by the patient's nose and thereforedisruption of the sealing force by movement in such a direction isminimised or eliminated.

Vent 3400

In one form, the patient interface 3000 may include a vent 3400constructed and arranged to allow for the washout of exhaled air(including exhaled carbon dioxide).

One form of vent 3400 in accordance with the present technologycomprises a plurality of very small holes, in other words, a multi-holevent. Two or more multi-hole vents may be provided on the frame 3310.They may be located on both sides of the connection port 3600 for an aircircuit 4170. These holes may be the interspaces between the fibers of atextile material. Alternatively, these holes may be microholes (1 micronor less) defined in a substrate of a semi-permeable material using alaser drill operating in the ultraviolet spectral range. Laser drilledmicroholes may be straight-walled or tapered/trumpet shaped. Another wayto create microholes is by using a chemical etchant after masking offareas of the substrate. There may be about 20 to about 80 holes or about32 to about 42 holes or about 36 to about 38 holes. In one example, ifthis form of vent 3400 is insert molded, the direction of the holesthrough the thickness of the vent 3400 may be modified to be skewedrather than perpendicular. This may avoid exhaled air (including exhaledcarbon dioxide) blowing directly into the face of a bed partner 1100 ifthe patient 1000 is facing him or her. In one example, the final numberof holes may be determined by blanking off some holes from an originallarger number of holes. For example, there may 40 holes and 2 holes areoccluded (by filling) so that the final number of holes is 38 holes. Theability to selectively occlude holes both in terms of the quantity andthe position of the holes to be occluded provide increased control overthe air flow rate and the air diffusion pattern.

Referring to FIGS. 146 to 152, the patient interface 3000 is a nasalpillows mask and preferably two vents 3400 are located in the plenumchamber 3200 of a mask frame 3310 or specifically located in a cushionclip (that may be preassembled with a cushion) of a mask frame 3310. Aconnection port 3600 or short tube 4180 is located between the two vents3400. Referring to FIGS. 153 and 154, a method for manufacturing apatient interface 3000 for the treatment of respiratory disorders isprovided. A porous textile is received (51) for processing. The methodcomprises cutting (57) a vent portion 72, 73 from the textile. Thetextile is formed by interlacing fibers to form an interlaced structuredefining tortuous air paths for air to pass therethrough. The textilehas a predetermined amount of porosity. The vent portion is held (59) ina mold. The held vent is permanently connected (60) to a mask frame3310. The vent portion and mask frame 3310 may both be made from aplastic material. This forms a vent 3400 for the patient interface 3000to washout exhaled air (including exhaled carbon dioxide).

Any type of cutting tool 67 may be used to cut the vent portion 72, 73from the textile 65, for example, a laser or mechanical cutter. Morethan one vent portion can be cut from the textile 65 at the same time,and preferably two vent portions are cut to form two vents at the sametime. If two are cut from roughly the same region of the textile 65, theairflow rate and material properties of the two vent portions maysometimes be substantially similar. This assists in determining andlocating defective material that has been supplied and also reduces theamount of calibration for equipment to adjust the airflow rate ifrequired. In another example, where heat staking by a staking punch 68is required, rather than cutting the vent portion 72, 73 before heatstaking, the vent portion 72, 73 can be cut from the textile 65 afterheat staking. In such a scenario, the first cutting by the cutter 67 canbe eliminated.

In one example of the present technology, the material of the interlacedfibers is a thermoset or thermoplastic which may include polyester,nylon, polyethylene and preferably polypropylene. In a specific example,the textile 65 may be SEFAR material Tetex Mono 05-1010-K 080 wovenpolypropylene material. A thermoset may also be used. The textile istypically provided in the form of a roll or ribbon 65 before the cuttingstep. The weave of the textile 65 is preferably a satin weave. However,other weaves are envisaged including plain weave, plain reverse Dutchweave and twill weave. The textile 65 may also be knitted (e.g. warpknitted) instead of woven. The voids or holes defined by the knit/weaveof fibers through the textile 65 do not necessarily have a uniformdimension since there is some variation between the positioning, spacingand compression of the fibers in the weave of the textile. The voids arepreferably not straight through holes but rather define a tortuous airflow path between adjacent fibers through the thickness of the textile65. A tortuous air flow path may have different pressure regions (higheror lower) along the air path. A tortuous air flow path significantlydiffuses the air flow and thereby reduces noise. If the voids werestraight through holes, then the fibers of the textile 65 may bearranged in the form of a mesh grid or a matrix. Advantageously, the airflow exiting from the vent 3400 is non-linear, avoids laminar flow and awide plume with turbulent flow is generated.

The patient interface 3000 includes nasal mask, full-face mask or nasalpillows. The mask frame 3310 of the patient interface 3000 has at leastone vent 3400, preferably, two vents 3400. If there are two vents 3400,a left vent is positioned on the left side of the anterior surface ofthe mask frame 3310 and a right vent is positioned on the right side ofthe anterior surface of the mask frame 3310. The left and right vents3400 are separated by an aperture or connection port 3600 for receivinga short tube 4180 operatively connected to a PAP device 4000.Alternatively, a single continuous vent 3400 positioned in the center ofthe mask frame 3310 is possible and the short tube 4180 is connected toa side of the mask frame 3310. The single continuous vent 3400 may havea superficial surface area equivalent to the combined superficialsurface area of two vents 3400.

In an example where two or more vents 3400 are provided to the maskframe 3310, the total or average airflow rate through all the vents 3400is used to obtain the desired airflow rate by selecting vent portionswith different airflow rates. For example, a first vent portion with alow airflow rate may be used with a second vent portion with a highairflow rate. The two vent portions combined may then provide an averageairflow rate that is the desired airflow rate.

The vent portion is cut or removed from the textile by laser cutting,ultrasonic cutting or mechanical cutting or heat cutting (using a hotanvil). Laser, ultrasonic and heat cutting because they cut and fuse theperipheral edge of the vent 3400 to eliminate stray fibers with looseends at the peripheral edge of the vent 3400. A laser cutter 69 can beused for laser cutting. Laser, ultrasonic and heat cutting also assistswith subsequent overmolding because it flattens the peripheral edge ofthe vent and makes it easier to overmold compared to an uneven edge.Consequently, trapped air bubbles are avoided at the bonding locationbetween the vent 3400 and mask frame 3310, resulting in the mask frame3310 with the integrated vent 3400 being highly visually appealing andstructurally reliable.

The permanent connection can be obtained by molecular adhesion usingovermolding, co-injection molding or two shot (2K) injection molding.This produces an integral bond and is strengthened when the materials ofthe vent portion with the mask frame 3310 interact by forming covalentbonds or hydrogen bonds. Some molds allow previously molded parts to bereinserted to allow a new plastic layer to form around the first part.This is referred to as overmolding. The overmolding process involves theuse of two materials to form one cohesive component. There are two typesof overmolding: insert and “two-shot (2K)”.

Two-shot or multi-shot molds are designed to “overmold” within a singlemolding cycle and must be processed on specialized injection moldingmachines with two or more injection units. This process is actually aninjection molding process performed twice. A high level of molecularadhesion is obtained. The method for manufacturing a patient interface3000 as described may be performed by overmolding the vent portion oftextile to the mask frame 3310. The vent portion is held in a mold 70and a molding machine 71 overmolds the vent portion to the mask frame3310. Since the textile 65 and mask frame 3310 are preferably made fromthe same plastic material, overmolding performs a fusion of materialbetween the vent portion of textile and mask frame 3310 which isstructurally strong and a permanent bond. In the final assembled patientinterface 3000, it is virtually undetectable by the unaided human eyethat the vent 3400 and mask frame 3310 are two distinct parts.

The vent 3400 has a maximum cross-sectional width of about 16 mm toabout 21 mm, preferably, 18.2 to 18.6 mm, and a maximum cross-sectionalheight of about 19 mm to about 25 mm, preferably, 21.6 mm to 22 mm, anda thickness of about 0.36 mm to about 0.495 mm, preferably, 0.40 to 0.45mm. Therefore the superficial area of two vents 3400 is about 800 mm².The superficial area of the porous region of the vent 3400 may be about201.6 mm² to about 278.6 mm², preferably, 240 mm². Therefore, for twovents 3400 the superficial area of the porous region is about 480 mm² to500 mm². The anterior side of the mask frame 3310 has a superficial areaof about 1800 mm². The superficial area of the vents 3400 comprises atleast 35% of the superficial area of the anterior side of the mask frame3310. Preferably, the two vents 3400 comprise 40% to 60% of the anteriorside of the mask frame 3310. Preferably, the two vents 3400 comprise 45%to 55% of the anterior side of the mask frame 3310. More preferably, thetwo vents 3400 comprise about 50% of the anterior side of the mask frame3310. The interlaced fibers of the vent 3400 provide a semi-rigid wovenstructure which it to form a significant area of the anterior surface ofthe mask frame 3310. The vent 3400 has sufficient rigidity that is ableto support its own weight under gravity and does not fold over itselfwhen there is tube torque, and is not floppy. Some prior masks with avent made of loose fabric cannot maintain their shape, geometry andprofile during breathing cycles of the patient (inhalation andexhalation) and therefore the vent will fold over itself during therapy.When such a prior vent folds over itself, the porous region of the ventis reduced by a percentage in a random manner because the folded oversections may partially or fully occlude the vent at these folded oversections. This leads to insufficient washout of exhaled air (includingexhaled carbon dioxide). In contrast, the vent 3400 of the presenttechnology does not fold over itself and therefore can ensure that theporous region of the vent 3400 maintains a substantially constant rateof washout for the exhaled air during breathing cycles of the patient1000 leading to proper washout of exhaled air (including exhaled carbondioxide) during therapy.

In one example, the airflow rate of the vent portion of the textile 65is first measured (52) by an airflow meter 66. A determination (53) ismade on whether there is a difference between the measured airflow rateand a desired airflow rate. If the airflow rate through the vent portionexceeds (56) a predetermined range, the amount of porosity of the ventportion is selectively reduced (54). The desired predetermined range isabout 42 to about 59 liters per minute at 20 cm H₂O pressure,preferably, about 47 to about 55 liters per minute at 20 cm H₂Opressure. For example, the airflow rate through the SEFAR material TetexMono 05-1010-K 080 woven polypropylene material may be about 37 to about64 liters at 20 cm H₂O pressure, preferably, about 42 to about 58 litersat 20 cm H₂O pressure. The variance over the length of the textile maybe sinusoidal over the length of the textile ribbon. Different areas ofthe textile when first received from a textile manufacturer may exhibitdifferent air flow rates due to the manufacturing process but notlimited to calendering without even heat and force distribution. Afterthe porosity of the vent portion has been reduced, the airflow rate ismeasured (55) again for verification to confirm it is now within thepredetermined range. The average diameter of the opening of the voids ispreferably less than 0.1 mm, and preferably provide a total open area(porous region) of approximately 1% to 10% of the superficial area ofthe vent 3400. For example, the total open area (porous region) may be22 mm² where the superficial area of the vent is 240 mm².

If the desired air flow rate exists in the textile 65, optionally, theholes in a peripheral edge region of a desired vent portion are occluded(56A). The peripheral edge region of the vent portion is overmolded tothe mask frame 3310. Since the holes that existed at the peripheral edgeregion have been occluded, the airflow rate of the vent portion shouldnot significantly differ after overmolding.

In some examples, the airflow rate may be measured (58) after the ventportion is cut from the textile, and also the vents may be measured (61)after being overmolded to the mask frame. This enables the airflow rateto be known and determined to be within the desired predetermined rangeafter certain manufacturing steps. This may prevent wastage so that thepart may be discarded as soon as it is known that it is not within thedesired predetermined range.

The porosity of the vent portion can be reduced by several ways,including: heat staking, plastic deformation by compression, ultrasonicwelding, applying a sealant (e.g. hot melt adhesive) and applying a thinfilm. Preferably, heat staking by a staking punch 68 is used to reduceporosity due to increased precision, greater certainty of occlusion ofholes in the textile, manufacturing speed, good visual appeal after heatstaking, and no additional material is required. Some material shrinkageoccurs when heating a plastic material which is accounted for by havingexcess material surrounding the specific physical dimension for theshape of the vent. The porosity of the vent portion is reduced bypartially occluding or by fully occluding holes in the vent portion. Thestaking punch 68 may use several heat weld heads of various sizes toperform the heat staking. The size of the heat weld head is selecteddepending on the airflow rate of the vent where a larger size is used ifthe airflow rate is very high.

The order of the cutting and porosity reduction steps may beinterchanged. In other words, the porosity reduction may be performedfirst on the textile 65 and then the vent portion is cut from thetextile 65. In such a scenario, the cutting by the cutter 67 can beeliminated.

Any area or region of the vent portion may be selected to reduceporosity. Preferably, the porosity of a substantially continuousperipheral edge region of the vent portion is reduced. This providesgood visual appeal because this is adjacent to or at the location wherethe vent portion is overmolded to the mask frame. Any visual differencesbetween the peripheral edge region and the rest of the vent portion maybe less noticeable to the human eye at this location since it may appearto be a defined edge of the mask frame 3310 for receiving the vent 3400.Alternatively, the area for porosity reduction may be in the form of acharacter/letter or logo in a central region 79 of the vent 3400 toenhance visual impact and improve brand awareness. It may also be usedas a replacement indicator for the patient 1000 to replace the vent 3400after a certain period of use.

After reducing the porosity of a region of the vent portion, the airflowrate of the vent portion is again measured by the airflow meter 66 toconfirm that the airflow rate is now within the desired predeterminedrange of about 47 to 53 liters per minute at 20 cm H₂O pressure. If theairflow rate is not within the desired predetermined range, then thevent portion may undergo heat staking again or the vent portion isdiscarded. This minimizes wastage by avoiding having to discard a maskframe with an overmolded defective vent, when only the defective ventportion can be discarded. In a further example for nasal pillows, italso avoids discarding a mask frame which has an air delivery tubeovermolded to it.

FIGS. 156 and 158 show a section of a textile 65 before heat staking.Loose ends 81 of vertically oriented fibers 80 (warp) along the top edgeof the textile 65 are visible. The opening of the voids 83 are definedbetween the vertically oriented fibers 80 and the horizontally orientedfibers 82 (weft). Some voids 83 are considered more porous than othervoids because they have a larger opening and therefore permit greaterairflow through it and increased exhaled air washout.

FIGS. 157 and 159 show a section of textile 65 after heat staking. Thevoids 83 that previously existed before heat staking have been occludedto reduce or prevent airflow through it. FIG. 157 is a graphicaldepiction for illustrative purposes only, however, a microscopephotograph is likely to show that discrete fibers of the textile afterheat staking are visually undetectable due to material deformation andmelting of the fibers caused by the heat and compression of the heatstaking process. The sectional side view depicted in FIG. 159illustrates that the discrete fibers of the textile 65 after heatstaking are visually undetectable due to material deformation andmelting of the fibers caused by the heat and compression of the heatstaking process. Therefore this region of the vent portion after heatstaking becomes substantially air impermeable, in order to selectivelyadjust the overall airflow rate of the entire vent portion.

Turning to FIG. 155, a section of textile 65 has two vent portions 72,73 that have been heat staked intended for left side and right sidevents. A notional left side vent portion 84 is also depicted showing theoutline of the vent portion prior to heat staking. The vent portions 72,73 are in the shape of a semi-circle or are D-shaped. Each vent portion72, 73 substantially conform to the shape of a vent aperture in the maskframe 3310. The vent portions 73, 73 are initially made slightly largerthan the vent aperture to assist with overmolding and also to take intoaccount plastic shrinkage that is expected due heat from the later stepsof heat staking and overmolding. Preferably, the peripheral edge of eachvent portion 72, 73 is continuously curved or arcuate with no straightlines. Two corners 74, 75 with an acute angle are the distal ends of alonger side 76 of the vent portion. The longer side 76 has a length ofabout 19 mm to about 24 mm, preferably, in the range of 21.6 mm to 22mm. Opposite the longer side 76 is a third corner 77 of the vent portionwith an obtuse angle. A substantially continuous peripheral edge region78 of the vent portion is heat staked to reduce porosity of the textilematerial 65 in this region. The peripheral edge region 78 may havelocation alignment features/pins. The width for the peripheral edgeregion 78 to be heat staked is selected based on the amount of porosityto be reduced in order to obtain the desired air flow rate overallthrough the vent. A central region 79 located within the peripheral edgeregion 78 has no heat staking applied to it, and the porosity remains asper the original textile 65.

Sound caused by exhaled air (including exhaled carbon dioxide) passingthrough the vent 3400 is minimised because of greater air diffusion asit passes through the textile/interlaced fibers, in particular, fornasal pillows when a patient 1000 exhales out of their nose and theexhaled air (including exhaled carbon dioxide) flows out through thevent 3400. Diffusion of the exhaled air (including exhaled carbondioxide) avoids direct or focused airflow to a bed partner 1100 or thepatient 1000 depending on vent orientation and sleeping position.Referring to FIGS. 167 to 175, in one example of the present technology,the vent 3400 is significantly more diffused than the multi-hole vent ofa SWIFT FX™ nasal pillows mask by ResMed Limited. Turning to FIG. 175,at close distances to the vent at about 100 mm, the air speed of exhaledair (including exhaled carbon dioxide) from the vent 3400 of the presenttechnology is about 5 times less than the SWIFT FX™ nasal pillows mask.In other words, the patient 1000 and their bed partner 1100 are lesslikely to feel the exhaled air (including exhaled carbon dioxide) fromthe vent 3400 compared to the multi-hole vent. This improves comfort forthe patient 1000 and their bed partner 1100. The average air velocityhas a non-linear curve and was measured using a directional hot wireanemometer in a closed room. Air velocity is a major factor on whetherexhaled air (including exhaled carbon dioxide) passing through the vent3400 may be felt by a person. Other factors which may affect what isfelt by a person that were not measured in FIGS. 167 to 175 includeambient room temperature, people's hair follicle density and people'sskin sensitivity. At greater distances from the vent, the air speed ofexhaled air (including exhaled carbon dioxide) from both vents willapproach zero and be indistinguishable from the surrounding ambientconditions. However, the air speed of exhaled air (including exhaledcarbon dioxide) from the vent 3400 of the present technology will reachthis limit of zero at a closer distance to the vent 3400 than themulti-hole vent. Although a specific multi-hole vent that has been usedin the SWIFT FX™ nasal pillows mask was compared, it is envisaged thatthe vent 3400 of the present technology is superior in terms of noiselevel and air diffusion compared to most multi-hole vents.

Another method for manufacturing a vent 3400 for washout of exhaled air(including exhaled carbon dioxide) from a patient interface 3000 is alsoprovided. A vent portion is cut from a semi-permeable material having athickness less than 0.45 mm and a predetermined amount of porosity todiffuse airflow. Cutting occurs if the semi-permeable material isprovided in the form of a larger sheet, ribbon or roll, particularlywith a large width. The vent portion is molecularly adhered to a maskframe 3310 of a patient interface to form the vent 3400. Thepredetermined amount of porosity is such that an airflow rate ofapproximately 47 to 53 liters per minute at 20 cm H₂O pressure ofrespiratory gas from the patient interface 3000 is obtained. Also, thepredetermined amount of porosity is such that an A-weighted sound powerlevel is less than or equal to 25 dbA, with uncertainty 3 dbA and anA-weighted sound pressure at a distance of 1 meter is less than or equalto 17 dbA with uncertainty 3 dbA are generated. Preferably theA-weighted sound power level dbA (uncertainty) is about 22.1 (3) dbA andthe A-weighted sound pressure dbA (uncertainty) is about 14.1 (3) dbAmeasured using ISO 17510-2:2007, 10 cmH2O pressure at 1 m. In otherwords, the vent 3400 of the present technology is quieter than themulti-hole vents of prior masks as described in the table of noise ofprior masks described under the heading of Description of the RelatedArt. The patient 1000 and their bed partner 1100 are less likely to hearsound caused by exhaled air (including exhaled carbon dioxide) passingthrough the vent 3400 compared to a multi-hole vent. Heat staking orother previously described techniques of occluding the holes may also beused to specifically adjust the airflow rate of the vent portion untilthe desired airflow rate is achieved, if necessary.

The vent portion 72 is held in a mold 70 to enable the vent portion 72to be overmolded to the mask frame 3310 in a molding machine 71. Thesemi-permeable material may be textile or non-textile so long as thethickness is less than about 0.45 mm. A thin vent is one feature thatenables a compact and unobtrusive patient interface 3000 to be provided.Also, a thin vent molded to the mask frame 3310 has visual appealbecause the fusion between these two parts appear seamless and flush andthe thin vent does not have to excessively protrude inwardly oroutwardly relative to the mask frame 3310. Also, a thin vent is lightweight since less material is required, reducing the overall weight ofthe patient interface 3000. For example, the textile material 65 mayweigh about 200 to 250 grams per m². The textile material 65 may weighabout 217 to about 234 grams per m². Smaller diameter fibers can producea thinner textile material to achieve the same air flow rate, and thiswould produce an more light weight vent 3400.

The vent 3400 of the patient interface 3000 is simple to clean and isre-usable. A mild cleaning solution or soapy water can be used to cleanthe vent 3400. Hot water can also be used to flow through the vent 3400for cleaning. The vent 3400 can be hand washed and rinsed withoutdisassembly from the mask frame 3310 because it is permanentlyconnected, for example, overmolded, to the mask frame 3310. Lessdetachable parts for the patient interface 3000 avoids the possibilityof losing individual parts and also reduces cleaning time by not havingto detach and re-attach many parts from one another. If the vent 3400 isformed by interlaced plastic fibers, durability of the vent 3400 ismaintained even after repeated cleaning in contrast to a vent made fromanother less durable material, for example, a cloth textile orGORE-TEX™. In contrast to the vent 3400 of the present technology,GORE-TEX™ is a non-woven material and its voids occlude very quicklyduring use from atmospheric particulate matter being trapped in thevoids, eventually leading to significant blockage of the vent. Blockageof the vent causes inadequate washout of exhaled air (including exhaledcarbon dioxide CO2) by the patient leading to an increase in CO2 levelsin the blood and ultimately hypoxia due to CO2 re-breathing. Also, thevoids in GORE-TEX™ are invisible to the naked eye meaning that thepatient is unable to visually determine blockage caused by mucous, dust,dirt, and grime. Washing the GORE-TEX™ material with water does notalleviate this problem because the purpose of GORE-TEX™ is to repelwater. In contrast to the vent 3400 of the present technology, GORE-TEX™is not a robust material as it is similar to paper and easily tears andsubject to damage easily if attempting to clean with a brush or fingers.This is a further reason that GORE-TEX™ cannot be cleaned and re-usedbecause it would be irreparably damaged by the cleaning process due toits paper like fragility. A sintered material such as a sinteredcylindrical block for a vent suffers similar deficiencies as withGORE-TEX™ in that the fine pores of the sintered material become cloggedafter use and cannot be properly cleaned for re-use and visualinspection of blockage is not discernible to the naked eye. Vents madefrom non-plastic materials are not as easily manufactured as the vent3400 of the present invention because they may require an additionalmanufacturing step or cannot be permanently connected to a mask frameusing an integral bond such as overmolding. Without an integral bondbetween the vent and the mask frame there may a reduction in durabilityand reliability, and/or the visual aesthetics are less pleasing.

In one example, the vent 3400 has consistent and continual air flowthrough the vent 3400 to enable proper washout of exhaled air (includingexhaled carbon dioxide). The vent 3400 is fast to manufacture and isfast to assemble thereby leading to low cost production compared to someprior art vent manufacturing methods. This may be attributed to itsrelatively simple geometric shape, low amount of processing steps tohave the vent 3400 permanently attached to the mask frame 3310, and alsoa low amount of processing steps and types of equipment needed in theevent adjustment to the airflow rate is required. Also, if the vent 3400is a textile formed by interlaced plastic fibers, it has a fabric lookwhich is aesthetically pleasing for patients 1000 and their bed partners1100 compared to a multi-hole vent or a sintered block vent.

Another example is described for manufacturing the vent 3400. Theplastic fibers are spun monofilaments and are woven or knitted on anarrow weaving loom into an interlaced structure. The interlacedstructure may be in the form of narrow ribbons, rather than a roll witha large width. Alternatively, the plastic fibers may be multifilamentwhich may provide tighter turns and more a tortuous path thanmonofilaments. This permits greater control of the permeability of thetextile 65 because heat slitting is avoided. Another advantage is thatthe heat staking step of the earlier example described for controllingand correcting the air flow rate can be avoided or the number of heatweld heads for the staking punch 68 may be reduced. Therefore, thetextile 65 of the vent 3400 may be manufactured within the desiredpredetermined range and heat staking is used only to blank off aperipheral edge area of the vent 3400 for the purposes of overmolding tothe mask frame 3310 for permanent attachment.

It may be possible to further limit any unintended variation of the airflow rate of the vent 3400 during manufacture. In the examples describedearlier, the roll or ribbon 65 may be calendered which is a finishingprocess where the roll or ribbon 65 is passed under rollers at hightemperatures and pressures to produce a flat sheet. However, in anotherexample, the roll or ribbon 65 may not be non-calendered first butinstead is first cut into narrow ribbons having a width substantiallysimilar to the height of the vent 3400. Each narrow ribbon is calenderedto make them flat using a heated roller that has a contact surface witha width substantially similar to the width of the ribbon, to ensure thatheat and pressure is applied evenly onto the ribbon. Therefore anyunintended variation of the air flow rate of the vent 3400 caused byuneven calendering may be avoided.

In another example, the textile 65 may be evenly calendered with apredetermined pressure and predetermined level of heat to achieve an airflow rate within the desired predetermined range. Thus, the earlierdescribed heat staking step for the purposes of adjusting the air flowrate by occluding voids may be avoided.

In another example, the textile 65 may omit calendering and voidocclusion. The textile 65 may be knit or woven into an interlacedstructure into narrow ribbons or strips. The textile 65 is then cutusing the cutting/fusing techniques described earlier into the shape ofthe vent portions 72, 73. The vent portions 72, 73 are then permanentlyconnected to the frame 3310 or other component in the pneumatic path ofthe patient interface 3000.

Although the vent 3400 has been described as being made from interlacedplastic fibers, it is envisaged that materials for the fibers apart thanplastic may be used that are biocompatible, and have a similar flexuralstiffness to prevent the shape, geometry, profile of the vent 3400 fromchanging during breathing cycles of the patient 1000. For example, thinmetallic wire or yarn may be used. An additive may be sprayed to stiffenthe metallic or yarn scaffold of the vent to provide a flexuralstiffness to prevent the shape, geometry, profile of the vent 3400 fromchanging during breathing cycles of the patient 1000. The vent 3400 isdescribed as having the form of an interlaced structure which includeswoven fibers and knitted fibers.

Location of Vent 3400

In one form of the present technology, vent 3400 is located on, orformed as part of frame 3310. Specifically, in the example of thetechnology depicted in FIGS. 75 and 76 a pair of vents 3400 may bedisposed on either side of an anterior surface of the frame 3310. In oneexample, the anterior surface of the mask frame 3310 is curved andtherefore the vents 3400 are not facing a direction that isperpendicular to the sagittal plane but are rather facing off theperpendicular axis between the sagittal plane and the coronal plane.Positioning the vents 3400 in this manner in the mask frame 3310 directsthe flow of air from the vents 3400 towards the lateral sides ratherthan straight centre which avoids a direct stream of air to a bedpartner 1100 if the patient 1000 is directly facing him or her. An areain front of the centre of the patient interface 3000 has a lower averageair velocity from the vents 3400 compared to an area along the vent axisi.e. the area along the direction perpendicular to the superficialanterior surface of the vent 3400.

Although the vent 3400 has been described as being permanently connectedto the frame 3310, it is envisaged that the vent 3400 may be locatedsomewhere else in the pneumatic region of the patient interface 3000,for example, on or proximal to the seal-forming structure 3100 or on acuff/adaptor 4190 (see FIGS. 1b and 1c ), which would allow the washoutof exhaled air (including exhaled carbon dioxide). The vent 3400 may bepermanently connected to the other pneumatic components in the pneumaticregion of the patient interface 3000, for example, on an elbow if thepatient interface 3000 has an elbow to decouple tube torque.

The pore size characterisation of the vent 3400 may be estimated using aBubble Point test method described in American Society for Testing andMaterials Standard (ASMT) Method F316. The Bubble Point test is asensitive visual technique. The textile material 65 may have a bubblepoint pressure of about 60 to about 100 psig (per square inch gauge).Preferably, the bubble point pressure of the textile material 65 has abubble point pressure of about 80 psig.

In one example of the present technology, the vent 3400 may be providedas a removable vent cap for a patient interface 3000. The vent cap has avent frame to removably engage with a vent orifice. The vent orifice maybe located in a mask frame, elbow or cushion member/plenum chamber 3200.The textile material 65 of the vent 3400 is permanently connected to thevent frame. The vent 3400 having a porous region for washout of exhaledair. The textile 65 in the form of interlaced fibers. A tortuous airpath for the exhaled air is defined by spaces between the interlacedfibers. The textile is structured such that the shape, geometry andprofile of the vent is substantially unchanged during breathing cyclesof the patient 1000 and the porous region maintains a substantiallyconstant rate of washout for the exhaled air.

Although the vent 3400 has been described as an interlaced structure, itmay be possible for the vent 3400 to have a non-woven structure such asa fiber reinforced polymer in the form of an unsealed and porous plasticmatrix. A two layered structure for the vent 3400 is possible by havinga non-woven structure as a first layer bonded to a woven structure as asecond layer.

Connection Port 3600

Connection port 3600 allows for connection of the patient interface 3000to a short tube 4180 of the air circuit 4170, as shown in FIG. 166. Inone example of the present technology, the short tube 4180 may beconnected directly to the patient interface 3000 by the connection port3600. The short tube 4180 may be connected to the frame 3310 at theconnection port 3600 by insert molding the frame onto the short tube4180. The connection port 3600 may be located on the patient interface3000 and may provide either a fixed or movable connection to the gasdelivery tube 4180.

The connection port 3600 may be part of the frame 3310 such that theframe is molded to include the connection port in one piece.Additionally, the connection port 3600 may be connected to the frame3310 at a limited portion or portions of its periphery. This may resultin open areas between the connection port 3600 and the frame 3310 andthese open areas may include the vent(s) 3400 described herein. As shownin FIGS. 10, 15 and 18, the connection port 3600 may be formed at anangle relative to the frame 3310 to direct the tube from the mask at anangle. Also, the connection port 3600 may be angled in any direction andat any angle relative to the frame 3310. In the illustrated example, theconnection port 3600 is angled downward relative to the frame 3310 tocater for a majority of patients who typically have the tube 4180directed downwards during treatment. This minimises looping of the tube4180 and may improve seal and stability of the patient interface 3000during treatment. It may also be possible to form the connection port3600 separately from the frame 3310 and connect these components suchthat the connection port 3600 may rotate relative to the frame 3310using a swivel connection. In such an example, may improve reduce tubetorque of the short tube 4180 disrupting sealing forces, or may improvecomfort and seal if the short tube 4180 is configured in a tube-upposition up over the patient's head.

FIG. 18 shows the short tube 4180 angled downwardly relative to thepatient interface 3000 by virtue of its connection to the connectionport 3600 which is formed at a downward angle relative to the frame3310. This arrangement may prevent the short tube 4180 from looping outaway from the patient at a great distance to avoid entanglement.

It should also be understood that the flow of gas into the patientinterface 3000 may be more evenly distributed in the example of thetechnology where no elbow is used to connect the air circuit 4170 to thepatient interface 3000. The sharp bend of an elbow may cause a largedensity of the flow lines on one side of the elbow. This may inducejetting where the flow is condensed and this may result in a suboptimalflow into the patient interface 3000 and, specifically, the nasalpillows 3130. It should also be understood that the vent 3400, describedabove, may contribute to the reduction in jetting. While the use ofelbows in prior masks have been to decouple tube torque by allowing atleast relative rotational movement between the air circuit 4170 and theframe 3310, one form of the present technology has a particularly floppyshort tube 4180 that is capable of decoupling tube torque thatconventional elbows would be responsible for.

Forehead Support

In one form of the present technology, patient interface 3000 does notinclude a forehead support. In one form, the patient interface 3000provides sufficient stability that a forehead support is not requiredwhich leads to less obtrusiveness and opens up the eyes and nasal bone.

In one alternative form, the patient interface 3000 includes a foreheadsupport.

Anti-Asphyxia

In one form of the present technology, patient interface 3000 mayinclude an anti-asphyxia valve (AAV). In further examples of the presenttechnology, when a full-face mask is used an AAV may be included withthe decoupling structure 4190 (see FIG. 1b ), the air circuit 4170 (seeFIGS. 1a to 1c ), or the patient interface 3000.

Ports

In one form of the present technology, patient interface 3000 mayinclude one or more supplemental oxygen ports 4185 that allow access tothe volume within the plenum chamber 3200. In one form this allows aclinician to supply supplemental oxygen. In one form this allows for thedirect measurement of a property gases within the plenum chamber 3200,such as the pressure.

Decoupling Structure(s) 4190

In one form, the patient interface 3000 includes at least one decouplingstructure, for example, a rotatable cuff or adapter 4190, as shown inFIGS. 1b and 1c , or a ball and socket. Referring to FIGS. 1b and 1c ,decoupling of a tube-drag force is provided at least in part by shorttube 4180. In this way, short tube 4180 functions at least in part as adecoupling structure 4190.

Referring to FIGS. 1b and 1c , at an end of the short tube 4180 is therotatable cuff or adapter 4190 to facilitate connection to a third endof an additional gas delivery tube 4178 that may be different in atleast one aspect from the short tube 4180. The rotatable cuff 4190allows the short tube 4180 and the additional gas delivery tube 4178 torotate relative to one another at respective ends. The additional gasdelivery tube 4178 may incorporate similar features to the short tube4180, but may have a larger inner diameter (e.g., 18 mm-22 mm). Thisadditional degree of freedom provided to the tubes may help to reducetube drag forces by alleviating twisting, and therefore kinking, of theair circuit 4170. Another end of the additional gas delivery tube 4178may be connected to a PAP device 4000.

Short Tube 4180

In one form of the present technology, a short tube 4180 is connected toframe 3310 at the connection port, as shown in FIG. 166, and forms partof the air circuit 4170.

The short tube 4180 is a gas delivery tube in accordance with an aspectof the present technology is constructed and arranged to allow a flow ofair or breathable gasses between the PAP device 4000 and the patientinterface 3000.

Gas delivery tubes are subject to tube drag forces which represent theforce subjected to the tube while in use as it lays on the patient andother surfaces (e.g., a bed, a nightstand, a hospital bed, a table,floor, etc.) during use. Since the short tube 4180 is connected to thepatient interface 3000 to provide breathable gas to the patient 1000these tube drag forces can affect the connection between the patientinterface 3000 and the patient 1000. For example, tension and torsiontube drag forces may cause the patient interface 3000 to displace fromthe patient's face, thereby causing leakage of the breathable gas fromthe patient interface 3000. Thus, it is desirable to decrease the tubedrag forces. This may be accomplished by reducing the weight of theshort tube 4180, improving its flexibility (e.g., by decreasing its bendradius such that the tube 4180 can be curved more tightly), and addingat least one degree of freedom for the short tube 4180. Also, such areduction in tube drag forces must be accomplished without significantlyreducing the strength of the tube 4180 such that it may resist occludingforces, e.g., when a patient may lay his or her arm on the tube 4180 orwhen twisted into a kinked position.

FIGS. 160 to 162 show three side views of an exemplary short tube 4180in three different states. FIG. 160 shows the short tube 4180 in aneutral state or normal condition. In the neutral state, the short tube4180 is not subject to any external forces, i.e., it is not stretched orcompressed. The short tube 4180 may be comprised of a web of material4172 that is spaced between adjacent coils of a helical coil 4174. Thehelical coil 4174 of the short tube 4180 may have a width of WC. The webof material 4172 may span the distance between adjacent coils WF.Further, as shown in FIG. 160, the web of material 4172 may be foldedsuch that a vertex or peak of the fold 4182 extends radially outwardfrom between adjacent coils. It should be understood that due to thefold of the web of material 4172, the width of material comprising theweb of material 4172 may be wider than the width between adjacent coilsWF. Also, the web of material 4172 may be folded along a predeterminedfold line 4186.

Also shown in FIG. 160, the distance between adjacent coils WF may beequal, or substantially equal, to the width of the helical coil WC whenthe short tube 4180 is in the neutral state. In such an arrangement, themaximum bend radius R (shown in FIG. 163) of the tube 4180 is decreasedand flexibility is improved. This is because an amount of materialgreater than in prior art tubes must be used to span the distancebetween adjacent coils. For one, the distance WF being equal to thewidth of the coil WC results in a larger amount of material to span thedistance, and because it is folded an even greater amount of materialmust be provided to comprise the web of material 4172. This principle isdescribed in greater detail in relation to FIG. 163. The shape of thefold is important to the overall flexibility of the tube. A largerradius in the folds of the web produces a more flexible tube. A verysharp crease makes the tube less flexible. After multiple thermaldisinfection cycles, the folds start to relax and the tube becomes lessflexible. When the fold is relaxed, it is observed that the folddiameter is reduced relative to the coil diameter and hence the peaks ofthe folds are lowered.

Additionally, in FIG. 160 it can be seen that the fold of the web ofmaterial 4172 extends not only radially outward from the short tube4180, but the fold of the web of material 4172 is centrally locatedbetween adjacent coils of the helical coil 4174. Furthermore, FIG. 160also shows how the slope of the web of material 4172 may increasetowards the vertex or peak of the fold 4182 from adjacent coils of thehelical coil 4174. In other words, the web of material 4172 is flatterfurther away from the predetermined fold line 4186 and the web ofmaterial 4172 becomes steeper and pointier near the vertex or peak ofthe fold 4182.

Also in FIG. 160, as will be discussed in greater detail below, it canbe seen that an outer portion or outer surface 4184 of the helical coil4174 has a curved profile that is rounded over a wide angle. In otherwords, the helical coil 4174 may have a profile of a portion of theperimeter of an oval. By providing a rounded outer surface or profile4184 to the helical coil 4174, a softer and smoother tactile feel may beprovided to the patient 1000. Additionally, this rounded outer surface4184 may also decrease the propensity of the short tube 4180 to snag onsurfaces while in use, such as bedding, the patient's clothing, bedroomor hospital furniture, etc. As can been in FIG. 160, a coil diameter DCcan be seen, which is the diameter of one of the plurality of helicalcoils measured perpendicularly to the longitudinal axis of the shorttube 4180.

Another feature that may be seen in FIG. 160, the short tube 4180, inits neutral state, has the fold of the web of material 4172 risingradially outward from the gas delivery tube such that the vertex or peakof the fold 4182 is at substantially the same height, or the sameheight, as the outer surface 4184 of the helical coil 4174. The fold ofthe web of material 4172 also defines a fold diameter DF betweenopposite vertices of the fold 4182 measured perpendicularly to thelongitudinal axis of the short tube 4180. Said in another way, when theshort tube 4180 is in its neutral state, the diameter of the web ofmaterial 4172 spanning respective vertices of its fold 4182 across thelongitudinal axis of the gas delivery tube may be equal to the diameterof the helical coil 4174 spanning respective outer surfaces 4184 acrossthe longitudinal axis. It could also be said that if the short tube 4180is laid out straight in a neutral state, that a single cylinder could becircumscribed flush to the vertex or peak of the fold 4182 and the outersurface 4184 of the helical coil 4174. Also, it may be said that whenthe short tube 4180 is in a neutral state that the fold diameter DF isequal to, or substantially equal to, the coil diameter DC.

Such an arrangement, in conjunction with the rounded outer profile 4184of the helical coil 4174, may provide an improved tactile feel, makingfor a smoother and softer feel for the patient. Additionally, the shorttube's 4180 decreased propensity to snag may also be enhanced by havingthe vertex or peak of the fold 4182 and the outer surface 4184 of thehelical coil 4174 rise to the same height because there is no singlesurface that protrudes prominently to snag on external surfaces.

In another example of the present technology, the web of material 4172may be folded multiple times in between adjacent coils of the helicalcoil 4174. This may allow for additional flexibility of the short tube4180 along with further extensibility due to the additional amount ofmaterial that is between each adjacent coil. Also, in another example ofthe present technology there may be certain regions or portions alongthe length of the short tube 4180 where the web of material 4172 isfolded between adjacent coils of the helical coil 4174 and other regionsof the gas delivery tube where the web of material is not folded. Suchan arrangement may allow for varying degrees of flexibility andextensibility along the length of the gas delivery tube. For example, itmay be possible to provide portions of the short tube 4180 withincreased or decreased stiffness at locations near the patient interface3000 and the PAP device 4000. In one example, portions of the short tube4180 near the patient interface 3000 and the PAP device 400 may havefewer folds per unit length of tube to increase the stiffness of thetube in these regions so as to ensure that kinking is reduced in theseregions. Another reason not to fold a section of web of material 4172could be for manufacturing reasons. For example, not having a fold onthe web 4172 at the distal ends where overmolding of a cuff is to occur.This may reduce the tendency of creating a weak spot in the web 4172where it joins the cuff as a folded web at these locations can getcaught in a weak pinched state.

FIG. 161 shows another side view of the exemplary short tube 4180. Inthis view, the short tube 4180 is in a compressed or contracted state.In this state, the length of the short tube 4180 will be less than itslength when it is in the neutral state shown in FIG. 160. For example,the short tube 4180 may be compressed to a length that is up to 50% lessthan in the neutral state. When the short tube 4180 is compressed to itscompressed state the web of material 4172 is compressed such that itsfold becomes steeper and the distance between adjacent coils WF of thehelical coil 4174 decreases. In the compressed state, the distancebetween adjacent coils WF may decrease to less than the width of thehelical coil WC. Also, the vertex or peak of the fold 4182 of the web ofmaterial 4172 may be forced further outward in the radial direction suchthat the vertex or peak rises above the outer surface 4184 of thehelical coil 4174. In other words the web of material 4172 may becometaller. This effect may be controlled by the amount of material betweenadjacent coils and the angle of the fold and the thickness TW of the webof material 4172. Moreover, it should also be understood that while thewidth of the helical coil WC may not decrease during compression of theshort tube 4180, the adjacent coils of the helical coil 4174 may beforced together as is common with other springs. Also in FIG. 161, itcan be seen that when the short tube 4180 is in the compressed state theangle at the vertex or peak 4182 of the fold of the web of material 4172(i.e., the angle between each portion of the web of material on eitherside of the predetermined fold line) is decreased and, again, the web ofmaterial may become taller.

FIG. 162 shows an additional side view of the short tube 4180 when it isin its extended or elongated state. In this state the short tube 4180may have a length greater than in the neutral state shown in FIG. 160.For example, the short tube 4180 may be extended up to 200% of itslength when in the neutral state. Also, in this view it can be seen thatthe distance between adjacent coils WF of the helical coil 4174increases and the fold of the web of material 4172 becomes flatter.Also, the distance between adjacent coils WF may increase to greaterthan the width of the helical coil WC. Further, in FIG. 162 it can beseen that the vertex or peak of the fold 4182 of the web of material4172 may be forced radially inward such that the vertex or peak descendsto below the height of the outer surface 4184 of the helical coil 4174.Again, this may be controlled by the amount of material between adjacentcoils and the angle of the fold. Moreover, it should also be understoodthat while the width of the helical coil WC may not increase duringextension of the short tube 4180, the adjacent coils of the helical coil4174 may be forced apart as is common with other springs. Also in FIG.162 it can be seen that when the short tube 4180 is in the extendedstate, the angle at the vertex or peak of the fold of the web ofmaterial (i.e., the angle between each portion of the web of material oneither side of the predetermined fold line) is increased and, again, theweb of material 4172 may become flatter.

FIG. 163 shows an exemplary short tube 4180 curved between two ends.When curved as shown in FIG. 163, the web of material 4172 betweenadjacent coils of the helical coil 4174 may be extended at the outerside of the curved portion 4179 and the web of material at the innerportion of the bend 4176 may be compressed. When curved such as this,the limits of the bend radius R may be better understood. In oneexample, when draped over a cylinder having a 13 mm diameter, the tubemay have a bend radius R of 44 mm under its own weight (i.e., with noadditional weight applied). The greater the amount of material thatcomprises the web of material 4172 the lower the possible bend radius Rbecause, as can be seen in FIG. 163, the outer side of the curvedportion 4179 can only be extended up to the maximum possible distancebetween adjacent coils WF. At the outer portion of the bend 4179 theshort tube 4180 can only bend and extend, at that outer portion 4179, upto the width of the web of material 4172 provided between adjacentcoils. Thus, if more material is provided for the web of material 4172between adjacent coils flexibility is improved because the short tube4180 can be flexed such that the outer portion of the bend 4179 isextended further and the maximum bend radius R is decreased.

Also, it can be seen that the distance between adjacent coils WF at theinside of the curved inner portion of the bend 4176 is decreased to thepoint that adjacent coils of the helical coil 4174 are nearly touching.Therefore, the bend radius R is also limited by the web of material 4172at the inner portion of the bend 4176. As can be seen in FIG. 164, theweb of material 4172 is compressed between adjacent coils of the helicalcoil 4174 at the inner portion of the bend 4176. Thus, the thicker theweb of material 4172 the greater the maximum bend radius R because thegreater the amount of material between adjacent coils, the less they areable to approach one another at the inner portion of the bend 4176.

Therefore, to optimize the bend radius R of the short tube 4180 asufficient width of the web of material 4172 must be provided to allowthe outer portion of the bend 4179 to extend to meet the desired bendradius, but also a sufficient thickness of the web of material must beprovided to allow adjacent coils of the helical coil 4174 to cometogether at the inner portion of the bend 4176 to achieve the desiredbend radius.

FIG. 164 shows a cross-sectional view of an exemplary short tube 4180taken as shown in FIG. 163. This cross-sectional view of the short tube4180 shows the gas delivery tube in its neutral state such that thedistance between adjacent coils WF is equal to the width of the helicalcoil WC. The short tube 4180 may also have an internal diameter DI thatis about 18 mm. The short tube 4180 may have a pitch P of between 3.2 mmto 4.7 mm, or preferably 4.5 mm to 4.7 mm. This view also shows that thehelical coil 4174 may have greater thickness TC than the thickness TW ofthe web of material 4172. With the helical coil 4174 being thicker thanthe web of material 4172, the helical coil is able to provide structuralstrength and this gives the short tube 4180 a spring effect. Also inthis view, it can be seen that the web of material 4172 may have asubstantially uniform and/or continuous thickness.

FIG. 164 also shows that at least a portion of the web of material 4172may be asymmetrical about the predetermined fold line 4186. For example,the web of material 4172 may include a humped portion 4181 adjacent tothe helical coil 4174 on one side of the predetermined fold line 4186and a slanted portion 4183 may be included on the other side adjacent tothe other side of the helical coil. Also, the slope of the web ofmaterial 4172 to the vertex or peak 4182 of the fold may be steeper onthe side of the slanted portion 4183 than on the side of the humpedportion 4181. Due to the different steepnesses, when the short tube 4180is in the neutral state, the width WFS between the edge of the helicalcoil on the side of the slanted portion 4183 and the predetermined foldline 4186 may be less than the width WFF between the edge of the helicalcoil on the side of the humped portion 4181 and the predetermined foldline. Thus, when extended, the web of material 4172 may be extended suchWFS may increase more than WFF because a greater amount of material iscomprised in that region. In other words, the short tube 4180 may beextended a certain amount in a first direction (e.g., from the slantedportion 4183 to the humped portion 4181) and a different amount in asecond direction opposite the first direction (e.g., from the humpedportion to the slanted portion). Such an arrangement may be advantageouswhere the patient interface 3000 is attached to the short tube 4180 atone end and the PAP device 4000 at the other, because the patient 1000may move while wearing the patient interface 3000, thus necessitating agreater amount of extensibility in the direction of the patient 1000.The asymmetric profile of the tube 4180 is typically a result of how thetube 4180 was made. Alternatively though, it may also be possible forthe web of material 4172 to have substantially symmetrical profile aboutthe predetermined fold line 4186.

The width of the humped portion WH and the width of the slanted portionWS may be different as can be seen in FIG. 164. Thus, the web ofmaterial 4172 may be flexed over a greater range toward the adjacentcoil across the slanted portion 4183 than across the humped portion4181. In other words, due to the larger gap at WS a greater amount offlexibility (i.e., smaller bend radius) may exist in this particularregion than at WH, which has a smaller gap. Also, because of the smallergap at WH this portion may be compressible to a lesser extent than atWS, because the web of material 4172 is already closer to the coil 4174at WH than at WS.

Another feature shown in FIG. 164 is that the superficial surface area(e.g., the outermost surface area of the short tube 4180) may becomprised in a greater proportion by the outer surface 4184 of thehelical coil 4174 than the web of material 4172 if the helix coil 4174generally feels better than the web 4172, particularly if the folds inthe web are very sharp. This may provide a better tactile feel for thepatient because, as can be seen in FIG. 164, the outer surface 4184 ofthe helical coil 4174 is rounded and therefore smoother than the vertexor peak of the fold 4182 of the web of material 4172.

Also it can be seen in FIG. 164 that the web of material 4172 and thehelical coil 4174 may be integrally bonded so that the interior surfaceof the short tube 4180 is smooth and continuous. It should be understoodthat either adjacent sides of the web of material 4172 may be joined toone another to form the smooth and continuous interior surface or theweb of material 4172 may be bonded to adjacent sides of adjacent coilsof the helical coil 4174. By forming the short tube 4180 in this manner,such that the interior surface is smooth and continuous, a smoother flowof breathable gas may be provided through the gas delivery tube.Typically, the folds are formed after the overmolding of the cuffs onboth ends of the short tube 4180 to prevent tape pinch.

It should also be understood that any suitable combination of materialsmay comprise the web of material 4172 and the helical coil 4174. Thematerials of each respective component 4172, 4174 may be the same orthey may be different in at least one aspect. In one example of thepresent technology, the web of material 4172 and the helical coil 4174may be made from a thermoplastic elastomer (TPE) or thermoplasticpolyurethane (TPU). The web 4172 and coil 4174 may both be made from thesame plastic material (or different blends of the same plastic material)which is advantageous to produce an integral chemical bond (molecularadhesion) between the web 4172 and the coil 4174. Material choices areconstrained by a number of factors. The mechanical properties of thematerial for the web 4172 for allowing flexibility are a decidingfactor. The ability to withstand thermal disinfection is anotherimportant factor. Not being sticky and tacky are other factors. Also,the short tube 4180 must avoid occlusion and withstand hoop stress whenan external force is applied on the circumferential surface of the tube4180 which may occur if a patient's limb lies on top of the short tube4180. This is addressed by providing the short tube 4180 with a minimuminternal diameter, and specifying the helix pitch and structuralrigidity of the helical coil 4174.

The choice of materials may also affect the spring stiffness (P=kx,where P is load, k is stiffness and x is deflection) of the short tube4180. The stiffer the spring k, the smaller the deflection under aconstant load. The spring rate is the amount of weight required todeflect a spring (any spring) per measurement unit. For example,materials having different moduli of elasticity and different flexuralstiffness may be used for the web of material 4172 and the helical coil4174, respectively, to create the desired spring stiffness. Similarly,the spring stiffness may also be chosen by using a material with thesame modulus of elasticity for both the web of material 4172 and helicalcoil 4174. Also, the pitch of the helical coil 4174, as discussed inreference to FIG. 164, may also affect the spring stiffness of the gasdelivery tube 4180. In one example, the spring stiffness may be about0.03 N/mm.

FIG. 165 shows another view of an exemplary short tube 4180 in a bent orcurved state. In this view, similar to FIG. 163, the short tube 4180 iscurved over a radius R. However, in this view the short tube 4180 can beseen draped over the edge of a flat, elevated surface (e.g., a table) todemonstrate how the tube 4180 might bend when subjected to tension atone end due to gravity. The weight of the portion of the short tube 4180that hangs over the corner of the table may cause extension of the tube4180 and bending at a region of the tube 4180 near the edge of thetable. This view depicts similar bending characteristics to those shownin FIG. 163. Specifically, the web of material 4172 is extended at theouter side of the bent region 4179 and compressed at the inner portionof the bend 4176, such that WF is greater at the outside of the curvethan on the inside.

FIG. 166 shows an exemplary short tube 4180 attached directly to apatient interface 3000. In prior masks, the gas delivery tube isattached to a mask through a swivelling elbow. By redirecting the gasdelivery tube with a swivelling elbow at its junction with the patientinterface, prior art assemblies seek to reduce tube drag forces.However, the inclusion of a swivelling elbow adds weight and parts whichcan, in turn, mitigate the reduction of tube drag forces. Thus, inaccordance with the present technology, the short tube 4180 may bedirectly connected to a mask frame 3310. FIG. 166 further shows that theshort tube 4180 may be angled downwardly from the connection to the maskframe 3310, which may also contribute to reducing tube drag forces. Thedownward angle may be facilitated in part by the connection port 3600.

Referring again to FIGS. 1b and 1c , a short tube 4180 according to thepresent technology can be seen connecting a patient interface 3000 at afirst end. This connection may be the fixed connection described abovein relation to FIG. 166. In this example, a cuff is overmolded on thefirst end of the tube 4180 which is then overmolded to a correspondingconnection port 3600 defined in the patient interface 3000. This exampleis elbow-less in the sense that there is no elbow between the tube 4180and the mask frame 3310. In other examples, it is possible for a swivelelbow to be positioned between the tube 4180 and the mask frame 3310 toenable the swivel elbow and the tube 4180 to freely rotate relative tothe mask frame 3310. It should be understood that the patient interfaces3000 shown in these views are shown in dashed lines to indicate that avariety of different patient interfaces may be connected to the shorttube 4180. At a second end of the short tube 4180 is a rotatable cuff,swivel cuff or adapter 4190 to facilitate connection to a third end ofan additional gas delivery tube 4178 that may be different from theshort tube 4180. The rotatable cuff allows the short tube 4180 and theadditional gas delivery tube 4178 to rotate relative to one another atrespective ends. The additional gas delivery tube 4178 may incorporatesimilar features to the short tube 4180, but may have a larger innerdiameter (e.g., 18 mm-22 mm). This additional degree of freedom providedto the tubes 4178, 4180 may help to reduce tube drag forces byalleviating twisting, decoupling any tube drag forces experienced, andtherefore kinking, of the short tube 4180. A fourth end of theadditional gas delivery tube 4178 may be connected to a PAP device 4000.A two part swivel that is snapped in is in-mold-assembled into the cuff.Alternatively, a one part swivel snapped on is possible.

Referring to FIGS. 203 to 222, the tube 4180 of the present technologyis compared to prior short tubes which have a helical coil. Thecomparison indicates that the flexural stiffness or floppiness of thetube 4180 of the present technology is superior because it has a lowergram-force (gf) when the tube 4180 is stretched. The lower end of thetubes is held in a fixed position such that the longitudinal axis of thetubes commences from an angle that is perpendicular to the direction offorce being applied to elongate the short tubes. In other words, thelower end of the short tube is held so that it is initially parallel andtangent to a horizontal surface (see FIGS. 203, 208, 213, 218). Theupper end of the short tubes is held by an Instron machine directlyabove the held lower end of the short tube. The Instron machinestretches the short tubes by a distance of 30 mm in a series of stepsfrom 0 to 30 mm, to 60 mm, to 90 mm and to 120 mm, in a verticallyupwards direction. The Instron machine also measures the force inNewtons at each distance which may correspond to the spring stiffness ofthe short tube. A torque gauge and force gauge (Torque Gauge RM No.MTSD05997 and Mecmesin Force Gauge RM No, MFGX05996) are used to measurethe grams-force at the fixed lower end of the short tube at eachdistance the short tube is elongated. Since the tubes having differentweights and lengths, at the initial position, the Instron machine,torque gauge and force gauge are zeroed. By zeroing the measurementequipment in this manner, the measurements would be independent ofweight and length of each tube. A 1 cm grid is also placed in thebackground to generally indicate the angle of the short tube at eachdistance. The comparison shows:

Tube 4180 of Present Technology (FIGS. 203 to 207) Distance Grams-ForceNewtons Force 0 0 0 30 mm 0 0 60 mm 40 0.2 N 90 mm 80 0.58 N  120 mm 140 2.2 N

ResMed ™ Swift FX ™ Nasal Pillows Mask tube (FIGS. 208 to 212) DistanceGrams-Force Newtons Force 0 0 0 30 mm 40 0.1 N 60 mm 120 0.32 N  90 mm320 1.1 N 120 mm  580 3.1 N

Philips Respironics ™ GoLife ™ Nasal Pillows Mask tube (FIGS. 213 to217) Distance Grams-Force Newtons Force 0 0 0 30 mm 60 0.24 N 60 mm 160 0.4 N 90 mm 500 0.71 N 120 mm  2820  6.6 N

Philips Respironics ™ Wisp ™ Nasal Mask tube (FIGS. 218 to 222) DistanceGrams-Force Newtons Force 0 0 0 30 mm 20 0.04 N 60 mm 120 0.17 N 90 mm300 0.73 N 120 mm  480  1.4 N

The comparison above shows that the short tube 4180 of the presenttechnology only begins to experience tube torque between 30 mm and 60 mmelongation whereas the prior tubes already experience tube torque by 30mm elongation. At every distance measured, the prior tubes have asignificantly higher grams-force indicating that they are less floppyand have a higher flexural stiffness compared to the tube 4180 of thepresent technology. Therefore seal disruption as a result of tube torqueis less likely to occur with the tube 4180 compared to prior tubes.Also, the floppiness of the tube 4180 enables it to be directlyconnected to the frame 3310 without requiring a swivel elbow or a balland socket elbow typically used to address tube torque. This eliminatesan additional part which leads to overall weight reduction for thepatient interface 3000. Comfort is improved because the tube 4180 isbarely felt by the patient 1000 and it provides a greater freedom ofmovement for the patient 1000 before any tube drag acts to pull theseal-forming structure 3100 off the patient's face.

As described above, as the short tube 4180 is moved relative to thepatient interface 3000, it may create tube drag forces. The tube dragforces herein may comprise forces and/or moments, however it willunderstood that the term tube drag forces encompasses forces and/ormoments unless stated otherwise.

One of the causes of such tube drag forces may be bending of the shorttube 4180. For instance, bending created in the short tube 4180 as thepatient 1000 turns their body away from the PAP device 4000 may resultin tube drag forces at the patient interface 3000, potentiallydisrupting the seal, and/or creating discomfort to the patient.

To demonstrate the effect of tube drag forces, a simplifiedrepresentation of a system comprising a patient interface 3000 and ashort tube 4180 may be considered. It may be assumed that in thissystem, the patient interface is placed on the patient 1000, and theheadgear is de-coupled from the patient interface. In this case, anytube drag forces must be reacted by the patient interface 3000, whereinany moments for instance may be reacted as a force couple on the patient1000, and/or any forces may be reacted by equal and opposite reactionforces on the patient 1000.

The resulting tube drag forces at the patient interface 3000 may berelated to the structure of the short tube 4180. More specifically, asthe short tube 4180 is bent, the bending stiffness of the short tube4180 may affect the tube drag forces created at the patient interface3000.

Typically, when a cylindrical tubular object of constant cross sectionis fixed at a fixed end and loaded at a free end (i.e. cantilevered),the resulting force and moment at the fixed end can be described as

$d = \frac{{Pl}^{3}}{3\; {EI}}$

(disregarding gravity) wherein d is the deflection, P is the verticalforce, l is the length of the tube, E is the elastic modulus of thematerial and I is the second moment of area of the cross-section. Here,the resulting reactions at the fixed end would be a vertical force of Pin the opposite direction, and a moment of lP.

Applying this to a system comprising a patient interface 3000 and ashort tube 4180, the reactions at the proximal end would be a verticalforce of P, and a moment of lP, which may form a part of the tube dragforce. The above equation may be rearranged to

$P = {\frac{3\; {dEI}}{l^{3}}.}$

It then follows that for a given deflection d (i.e. for a given movementby the patient 1000), and tube length l, the tube drag force would beincreased as EI is increased, or as EI is decreased, tube drag would bedecreased.

For a circular tube of constant cross section, I may be calculated usingthe equation

$I = {\frac{\pi \left( {d_{o}^{4} - d_{i}^{4}} \right)}{64}.}$

Therefore, as an example, for a given inner diameter (d_(i)) of 15 mm, adecrease in the outer diameter (d_(o)) from 19 mm to 18 mm woulddecrease tube drag forces by approximately 32%. Similarly, a decrease inthe elastic modulus in the material used would achieve a decrease intube drag forces, although the relationship may be linear in this case.

Therefore, while the short tube 4180 in the present technology may notbe a circular tube of constant cross section, the total bendingstiffness of the short tube 4180 may be a result of geometric andmaterial properties of various portions of the short tube 4180, such asthe web of material 4172 and the helical coil 4174.

Reducing the bending stiffness of the short tube 4180 may result inweakening the structural integrity of the short tube 4180. That is, asan example, if the thickness of the web of material 4172 was changed byreducing the outer diameter of the short tube 4180, the bendingstiffness and therefore tube drag forces may be reduced, however thismay result in a more fragile construction of the short tube 4180 andlead to occlusion of the short tube 4180 during normal use.

Therefore an advantage of the present technology is the combination ofthe geometry and material of the short tube 4180 working to reducebending stiffness while maintaining appropriate strength to avoidocclusion and be durable.

The tube 4180 is substantially silent without a sticky noise/stictionthat may occur from axial compression and elongation of the tube 4180.One example to reduce or eliminate noise may be applying an additive toprevent the coils of the helical coil 4174 sticking to each other. Priortubes for patient interfaces have been known to suffer from this type ofnoise which can be annoying to the patient 1000 and their bed partner1100 when trying to sleep as it is intermittent noise. The tube 4180 isintended to be light weight to minimise tube drag forces caused by theweight of the tube 4180 under gravity. In one example of the presenttechnology, in the neutral state, the length of the tube 4180 may beabout 285 mm to 305 mm including the end cuffs and may weigh about 18.7grams to 19.1 grams. Thus, the weight of the tube 4180 with the endcuffs may be about 62.6 g/m to 65.6 g/m. There is no air leak betweenthe tube 4180 and the end cuffs that are overmolded to the ends of thetube 4180. One of the end cuffs may be a swivel cuff 4190 to allow 360°relative rotation between the short tube 4180 and the long tube 4178,while the other end cuff is a frame cuff that does not swivel. Theswivel cuff 4190 may have a bump off which provides an external tactilecircumferential edge for an index finger of the patient 1000 todisengage the tube 4180 from a tube adapter 4190 connected to a longtube 4178. The bump off may tolerate a higher force to enhancedurability of the swivel end cuff 4190 and short tube 4180 afterrepetitive engagement and disengagement from the long tube 4178.

Although a single helical coil 4174 has been described, it is envisagedthat more than helical coil may be provided for the tube 4180. Multiplehelical coils for the tube 4180 enable multi-start (double start, triplestart, etc), in other words, more than one thread. This may permit eachhelical coil to be made from a different material or have differentdimensions in order to enhance floppiness of the tube 4180 for reducingtube drag forces but also to prevent or resist kinking and occlusion byhaving a strong structure.

Mask System

One or more of the mask components may configured and arranged togetherto decouple tube torque to minimise the likelihood of seal disruption.The short tube 4180 is able to decouple tube torque because of itsenhanced floppiness and ability to stretch. If tube torque is greaterthan what the short tube 4180 can decouple, the positioning andstabilising structure 3300 also decouples tube torque. The rigidiserarms 3302 flex in the sagittal plane to decouple tube torque. Also, thecushioning function of the plenum chamber 3200 and/or seal-formingstructure 3100 will decouple some amount of tube torque. Any combinationof two or more of these features improves the ability to decouple tubetorque. The combination of all of these features further enhances theability to decouple a larger amount of tube torque.

One or more of the mask components may be configured and arrangedtogether to improve comfort for the patient 1000. The short tube 4180 islight weight and the plenum chamber 3200 and seal-forming structure 3100are also light weight therefore the headgear tension provided by thepositioning and stabilising structure 3300 is not required to beuncomfortably high in order to provide a good seal. Reducing the needfor an elbow to connect the short tube 4180 to the frame 3310 alsoreduces overall weight of the patient interface 3000 which lowers thelevel of headgear tension required by the positioning and stabilisingstructure 3300. Also, the perception by the patient 1000 when a patientinterface 3000 is light weight is that it is “barely there” such that itdoes not feel like you are wearing a patient interface 3000 leading toless anxiety and claustrophobia. The shape and flexibility of therigidiser arms 3302 provide comfort for the patient 1000 because theysit under the cheek bones and also direct the headgear strap 3301 aroundthe patient's ears which may be sensitive facial regions for somepatients 1000. The strap 3301 is made from a fabric textile and feelsgood against the patient's skin because it does not retain surface heatand condensate from perspiration compared to a plastic headgear strap.Also, the strap 3301 being made from a fabric textile is less dense thana plastic material which leads to weight and bulk reduction. The splitregion 3326 of the strap 3301 enables the patient 1000 to adjustheadgear tension to a level they feel is comfortable for them. Anycombination of two or more of these features improves comfort for thepatient 1000. The combination of all of these features greatly enhancescomfort for the patient 1000.

One or more of the mask components may be configured and arrangedtogether to improve the chances of an optimal seal with the patient1000. This may lead to better therapy compliance and an increase inaverage daily usage by an additional 36 minutes. An optimal seal may beobtained through a combination of improved decoupling of tube torque andalso enhanced comfort for the patient 1000 as described above.

One or more of the mask components may be configured and arrangedtogether to improve the visual appeal of the patient interface 3000leading to better therapy compliance, especially for first time patients1000. The patient interface 3000 has a low profile and small footprinton the patient's face because the frame 3310 is not very wide and isalso curved to correspond to facial geometry. Also, the unitary strap3301 with the split region 3326 and the smooth continuous surface of thecurved profile of rigidiser arm 3323 is not obtrusive, does not appearbulky or complex and does not cover a large surface area of thepatient's face. Any combination of two or more of these featuresimproves the visual appeal of the patient interface 3000. Thecombination of all of these features greatly enhances the visual appealof the patient interface 3000.

One or more of the mask components may be configured and arrangedtogether to improve assembly and disassembly of the patient interface3000. The patient interface 3000 provides simplicity to the patient 1000as there are two detachable components from the frame 3310, which arethe seal-forming structure 3100 and strap 3301. Less detachablecomponents also means that the patient interface 3000 is easy toassembly and disassemble when the patient interface 3000 needs to becleaned. The frame 3310, plenum chamber 3200/seal-forming structure 3100and strap 3301 may be washed individually and on different schedules,for example, the plenum chamber 3200/seal-forming structure 3100 may bewashed more frequently than the strap 3301. The shape and structure ofthe components visually and tactilely suggest to the patient 1000 how toassemble and disassemble the patient interface 3000 in an intuitivemanner. For example, the mating relationship between the plenum chamber3200 and the frame 3310 which generates an audible click sound whenengagement is correct is intuitive to a patient 1000. Also, providingvisual and tactile indicators on the frame 3310, plenum chamber 3200 andthe positioning and stabilising structure 3300 adds a further guide forthe patient 1000 to avoid incorrect assembly/disassembly ormisorientation/misalignment of mask components. Some of these featuresare especially advantageous for patients 1000 in a darkened environmentwho may have arthritic hands. For example, the audible click sound maybe heard, or the touch and feel of the shapes of the mask components andtactile indicators are also useful in low lighting conditions. Also, bysimply stretching the strap 3301 to don or doff the patient interface300 from the patient's face avoids complicated engagement/disengagementprocedures. Any combination of two or more of these features improvesthe simplicity of the patient interface 3000. The combination of all ofthese features greatly enhances the simplicity of the patient interface3000.

In one example of the present technology, a frame assembly includes thesub-assemblies of the frame 3310, short tube 4180, vent 3400 andrigidiser arms 3302. The sub-assemblies of the frame assembly arepermanently connected to each other, for example, the frame 3310 andshort tube 4180 are permanently connected to each other, the frame 3310and rigidiser arms 3302 are permanently connected to each other, and theframe 3310 and the vent 3400 are permanently connected to each other. Acushion assembly is removably engageable with the frame assembly. Thecushion assembly includes the seal-forming structure 3100, plenumchamber 3200, retaining structure 3242, and plenum connection region3240. The strap 3301 is removably engageable with the frame assembly, inparticular, with the rigidiser arms 3302.

Although a strap 3301 made from fabric has been described, it isenvisaged that the strap may be made from silicone or a plastic materialat least at a distal end. A silicone strap enables overmolding to theplenum chamber 3200 for a permanent connection.

Preventing Incorrect Assembly and Disassembly of Mask System

Referring to FIGS. 187 to 190, the patient interface 3000 is providedwith visual indicators and tactile indicators to prevent or minimisemisorientation when engaging mask components together. They also provideintuitiveness to patients 1000 when disengaging mask components fromeach other. In FIGS. 187 and 188, on the outer surface 3355 of theextension 3350 of the rigidiser arms 3302 there is pad printing 3290provided. The mask name and brand logo are pad printed indicateorientation to the patient 1000 where the words are oriented the rightside up. These provide a visual indication for the patient 1000. In FIG.189, there is raised/embossed text 3291 near an upper edge the frame3310. This provides the patient 1000 with a visual and tactile indicatorof the whether the frame 3310 is oriented up or down, and especiallyuseful in low light conditions when attaching the strap 3301 to therigidiser arm 3302. Also, there is recessed text 3292 on the outersurface of the rigidiser arm 3302. This provides the patient 1000 with avisual and tactile indicator of the orientation of the rigidiser arm3302 and is helpful when attaching the strap 3301 to the rigidiser arm3302. There may be pad printing 3293 on one side of the plenum chamber3200. The pad printing 3293 may indicate the Left pillow 3130 and Rightpillow 3130 and also the size of the seal-forming structure 3100 (Small,Medium, Large). For example, when the patient 1000 sees the pad printing3293 on the plenum chamber 3200, they would be aware that they arefacing the top surface of the plenum chamber 3200. All these visual andtactile indicators assist the patient 1000 in identifying the sides andsurfaces of the patient interface 3000 to avoid misorientation andimproper assembly and disassembly. This may avoid inadvertent damage tothe patient interface 3000 and also ease any user frustration associatedwith assembly and disassembly.

PAP Device 4000

A PAP device 4000 in accordance with one aspect of the presenttechnology comprises mechanical and pneumatic components 4100,electrical components 4200 and is programmed to execute one or morealgorithms 4300. The PAP device may have an external housing 4010,formed in two parts, an upper portion 4012 of the external housing 4010,and a lower portion 4014 of the external housing 4010. In alternativeforms, the external housing 4010 may include one or more panel(s) 4015.The PAP device 4000 may comprise a chassis 4016 that supports one ormore internal components of the PAP device 4000. In one form a pneumaticblock 4020 is supported by, or formed as part of the chassis 4016. ThePAP device 4000 may include a handle 4018.

The pneumatic path of the PAP device 4000 may comprise an inlet airfilter 4112, an inlet muffler, a controllable pressure device capable ofsupplying air at positive pressure (e.g., a controllable blower 4142),and an outlet muffler. One or more pressure sensors and flow sensors maybe included in the pneumatic path.

The pneumatic block 4020 may comprise a portion of the pneumatic paththat is located within the external housing 4010.

The PAP device 4000 may have an electrical power supply 4210 and one ormore input devices 4220. Electrical components 4200 may be mounted on asingle Printed Circuit Board Assembly (PCBA) 4202. In an alternativeform, the PAP device 4000 may include more than one PCBA 4202.

PAP Device Mechanical & Pneumatic Components 4100 Air Filter(s) 4110

A PAP device 4000 in accordance with one form of the present technologymay include an air filter 4110, or a plurality of air filters 4110.

In one form, an inlet air filter 4112 is located at the beginning of thepneumatic path upstream of a controllable blower 4142. See FIG. 3 c.

In one form, an outlet air filter 4114, for example an antibacterialfilter, is located between an outlet of the pneumatic block 4020 and apatient interface 3000. See FIG. 3 c.

Pressure Device 4140

In a form of the present technology, a pressure device for producing aflow of air at positive pressure is a controllable blower 4142. Forexample the blower 4142 may include a brushless DC motor with one ormore impellers housed in a volute. The blower 4142 may be capable ofdelivering a supply of air, for example about 120 litres/minute, at apositive pressure in a range from about 4 cmH2O to about 20 cmH2O, or inother forms up to about 30 cmH2O.

Humidifier 5000 Humidifier Overview

In one form of the present technology there is provided a humidifier5000, as shown in FIG. 3b , that may comprise a water reservoir and aheating plate.

Glossary

For the purposes of the present technology disclosure, in certain formsof the present technology, one or more of the following definitions mayapply. In other forms of the present technology, alternative definitionsmay apply.

General

Air: In certain forms of the present technology, air supplied to apatient may be atmospheric air, and in other forms of the presenttechnology atmospheric air may be supplemented with oxygen.

Continuous Positive Airway Pressure (CPAP): CPAP treatment will be takento mean the application of a supply of air or breathable gas to theentrance to the airways at a pressure that is continuously positive withrespect to atmosphere, and preferably approximately constant through arespiratory cycle of a patient. In some forms, the pressure at theentrance to the airways will vary by a few centimeters of water within asingle respiratory cycle, for example being higher during inhalation andlower during exhalation. In some forms, the pressure at the entrance tothe airways will be slightly higher during exhalation, and slightlylower during inhalation. In some forms, the pressure will vary betweendifferent respiratory cycles of the patient, for example being increasedin response to detection of indications of partial upper airwayobstruction, and decreased in the absence of indications of partialupper airway obstruction.

Aspects of PAP Devices

Air circuit: A conduit or tube constructed and arranged in use todeliver a supply of air or breathable gas between a PAP device and apatient interface. In particular, the air circuit may be in fluidconnection with the outlet of the pneumatic block and the patientinterface. The air circuit may be referred to as air delivery tube. Insome cases there may be separate limbs of the circuit for inhalation andexhalation. In other cases a single limb is used.

APAP: Automatic Positive Airway Pressure. Positive airway pressure thatis continually adjustable between minimum and maximum limits, dependingon the presence or absence of indications of SDB events.

Blower or flow generator: A device that delivers a flow of air at apressure above ambient pressure.

Controller: A device, or portion of a device that adjusts an outputbased on an input. For example one form of controller has a variablethat is under control—the control variable—that constitutes the input tothe device. The output of the device is a function of the current valueof the control variable, and a set point for the variable. Aservo-ventilator may include a controller that has ventilation as aninput, a target ventilation as the set point, and level of pressuresupport as an output. Other forms of input may be one or more of oxygensaturation (SaO2), partial pressure of carbon dioxide (PCO2), movement,a signal from a photoplethysmogram, and peak flow. The set point of thecontroller may be one or more of fixed, variable or learned. Forexample, the set point in a ventilator may be a long term average of themeasured ventilation of a patient. Another ventilator may have aventilation set point that changes with time. A pressure controller maybe configured to control a blower or pump to deliver air at a particularpressure.

Therapy: Therapy in the present context may be one or more of positivepressure therapy, oxygen therapy, carbon dioxide therapy, control ofdead space, and the administration of a drug.

Motor: A device for converting electrical energy into rotary movement ofa member. In the present context the rotating member is an impeller,which rotates in place around a fixed axis so as to impart a pressureincrease to air moving along the axis of rotation.

Positive Airway Pressure (PAP) device: A device for providing a supplyof air at positive pressure to the airways.

Transducers: A device for converting one form of energy or signal intoanother. A transducer may be a sensor or detector for convertingmechanical energy (such as movement) into an electrical signal. Examplesof transducers include pressure sensors, flow sensors, carbon dioxide(CO2) sensors, oxygen (O2) sensors, effort sensors, movement sensors,noise sensors, a plethysmograph, and cameras.

Aspects of the Respiratory Cycle

Apnea: Preferably, apnea will be said to have occurred when flow fallsbelow a predetermined threshold for a duration, e.g. 10 seconds. Anobstructive apnea will be said to have occurred when, despite patienteffort, some obstruction of the airway does not allow air to flow. Acentral apnea will be said to have occurred when an apnea is detectedthat is due to a reduction in breathing effort, or the absence ofbreathing effort.

Duty cycle: The ratio of inhalation time, Ti to total breath time, Ttot.

Effort (breathing): Preferably breathing effort will be said to be thework done by a spontaneously breathing person attempting to breathe.

Expiratory portion of a breathing cycle: The period from the start ofexpiratory flow to the start of inspiratory flow.

Flow limitation: Preferably, flow limitation will be taken to be thestate of affairs in a patient's respiration where an increase in effortby the patient does not give rise to a corresponding increase in flow.Where flow limitation occurs during an inspiratory portion of thebreathing cycle it may be described as inspiratory flow limitation.Where flow limitation occurs during an expiratory portion of thebreathing cycle it may be described as expiratory flow limitation.

Hypopnea: Preferably, a hypopnea will be taken to be a reduction inflow, but not a cessation of flow. In one form, a hypopnea may be saidto have occurred when there is a reduction in flow below a threshold fora duration. In one form in adults, the following either of the followingmay be regarded as being hypopneas:

(i) a 30% reduction in patient breathing for at least 10 seconds plus anassociated 4% desaturation; or(ii) a reduction in patient breathing (but less than 50%) for at least10 seconds, with an associated desaturation of at least 3% or anarousal.

Inspiratory portion of a breathing cycle: Preferably the period from thestart of inspiratory flow to the start of expiratory flow will be takento be the inspiratory portion of a breathing cycle.

Patency (airway): The degree of the airway being open, or the extent towhich the airway is open. A patent airway is open. Airway patency may bequantified, for example with a value of one (1) being patent, and avalue of zero (0), being closed.

Positive End-Expiratory Pressure (PEEP): The pressure above atmospherein the lungs that exists at the end of expiration.

Peak flow (Qpeak): The maximum value of flow during the inspiratoryportion of the respiratory flow waveform.

Respiratory flow, airflow, patient airflow, respiratory airflow (Qr):These synonymous terms may be understood to refer to the PAP device'sestimate of respiratory airflow, as opposed to “true respiratory flow”or “true respiratory airflow”, which is the actual respiratory flowexperienced by the patient, usually expressed in litres per minute.

Tidal volume (Vt): The volume of air inhaled or exhaled during normalbreathing, when extra effort is not applied.

(inhalation) Time (Ti): The duration of the inspiratory portion of therespiratory flow waveform.

(exhalation) Time (Te): The duration of the expiratory portion of therespiratory flow waveform.

(total) Time (Ttot): The total duration between the start of theinspiratory portion of one respiratory flow waveform and the start ofthe inspiratory portion of the following respiratory flow waveform.

Typical recent ventilation: The value of ventilation around which recentvalues over some predetermined timescale tend to cluster, that is, ameasure of the central tendency of the recent values of ventilation.

Upper airway obstruction (UAO): includes both partial and total upperairway obstruction. This may be associated with a state of flowlimitation, in which the level of flow increases only slightly or mayeven decrease as the pressure difference across the upper airwayincreases (Starling resistor behaviour).

Ventilation (Vent): A measure of the total amount of gas being exchangedby the patient's respiratory system, including both inspiratory andexpiratory flow, per unit time. When expressed as a volume per minute,this quantity is often referred to as “minute ventilation”. Minuteventilation is sometimes given simply as a volume, understood to be thevolume per minute.

PAP Device Parameters

Flow rate: The instantaneous volume (or mass) of air delivered per unittime. While flow rate and ventilation have the same dimensions of volumeor mass per unit time, flow rate is measured over a much shorter periodof time. Flow may be nominally positive for the inspiratory portion of abreathing cycle of a patient, and hence negative for the expiratoryportion of the breathing cycle of a patient. In some cases, a referenceto flow rate will be a reference to a scalar quantity, namely a quantityhaving magnitude only. In other cases, a reference to flow rate will bea reference to a vector quantity, namely a quantity having bothmagnitude and direction. Flow will be given the symbol Q. Total flow,Qt, is the flow of air leaving the PAP device. Vent flow, Qv, is theflow of air leaving a vent to allow washout of exhaled gases. Leak flow,Ql, is the flow rate of unintentional leak from a patient interfacesystem. Respiratory flow, Qr, is the flow of air that is received intothe patient's respiratory system.

Leak: Preferably, the word leak will be taken to be a flow of air to theambient. Leak may be intentional, for example to allow for the washoutof exhaled CO₂. Leak may be unintentional, for example, as the result ofan incomplete seal between a mask and a patient's face.

Pressure: Force per unit area. Pressure may be measured in a range ofunits, including cmH2O, g-f/cm², hectopascal. 1cmH₂O is equal to 1g-f/cm² and is approximately 0.98 hectopascal. In this specification,unless otherwise stated, pressure is given in units of cmH2O. For nasalCPAP treatment of OSA, a reference to treatment pressure is a referenceto a pressure in the range of about 4-20 cmH2O, or about 4-30 cmH2O. Thepressure in the patient interface is given the symbol Pm.

Sound Power: The energy per unit time carried by a sound wave. The soundpower is proportional to the square of sound pressure multiplied by thearea of the wavefront. Sound power is usually given in decibels SWL,that is, decibels relative to a reference power, normally taken as 10⁻¹²watt.

Sound Pressure: The local deviation from ambient pressure at a giventime instant as a result of a sound wave travelling through a medium.Sound power is usually given in decibels SPL, that is, decibels relativeto a reference power, normally taken as 20×10′ pascal (Pa), consideredthe threshold of human hearing.

Anatomy of the Face

Ala: the external outer wall or “wing” of each nostril (plural: alar)

Alare: The most lateral point on the nasal ala.

Alar curvature (or alar crest) point: The most posterior point in thecurved base line of each ala, found in the crease formed by the union ofthe ala with the cheek.

Auricula or Pinna: The whole external visible part of the ear.

(nose) Bony framework: The bony framework of the nose comprises thenasal bones, the frontal process of the maxillae and the nasal part ofthe frontal bone.

(nose) Cartilaginous framework: The cartilaginous framework of the nosecomprises the septal, lateral, major and minor cartilages.

Columella: the strip of skin that separates the nares and which runsfrom the pronasale to the upper lip.

Columella angle: The angle between the line drawn through the midpointof the nostril aperture and a line drawn perpendicular to the Frankfurthorizontal while intersecting subnasale.

Frankfort horizontal plane: A line extending from the most inferiorpoint of the orbital margin to the left tragion. The tragion is thedeepest point in the notch superior to the tragus of the auricle.

Glabella: Located on the soft tissue, the most prominent point in themidsagittal plane of the forehead.

Lateral nasal cartilage: A generally triangular plate of cartilage. Itssuperior margin is attached to the nasal bone and frontal process of themaxilla, and its inferior margin is connected to the greater alarcartilage.

Greater alar cartilage: A plate of cartilage lying below the lateralnasal cartilage. It is curved around the anterior part of the naris. Itsposterior end is connected to the frontal process of the maxilla by atough fibrous membrane containing three or four minor cartilages of theala.

Nares (Nostrils): Approximately ellipsoidal apertures forming theentrance to the nasal cavity. The singular form of nares is naris(nostril). The nares are separated by the nasal septum.

Naso-labial sulcus or Naso-labial fold: The skin fold or groove thatruns from each side of the nose to the corners of the mouth, separatingthe cheeks from the upper lip.

Naso-labial angle: The angle between the columella and the upper lip,while intersecting subnasale.

Otobasion inferior: The lowest point of attachment of the auricle to theskin of the face.

Otobasion superior: The highest point of attachment of the auricle tothe skin of the face.

Pronasale: the most protruded point or tip of the nose, which can beidentified in lateral view of the rest of the portion of the head.

Philtrum: the midline groove that runs from lower border of the nasalseptum to the top of the lip in the upper lip region.

Pogonion: Located on the soft tissue, the most anterior midpoint of thechin.

Ridge (nasal): The nasal ridge is the midline prominence of the nose,extending from the Sellion to the Pronasale.

Sagittal plane: A vertical plane that passes from anterior (front) toposterior (rear) dividing the body into right and left halves.

Sellion: Located on the soft tissue, the most concave point overlyingthe area of the frontonasal suture.

Septal cartilage (nasal): The nasal septal cartilage forms part of theseptum and divides the front part of the nasal cavity.

Subalare: The point at the lower margin of the alar base, where the alarbase joins with the skin of the superior (upper) lip.

Subnasal point: Located on the soft tissue, the point at which thecolumella merges with the upper lip in the midsagittal plane.

Supramentale: The point of greatest concavity in the midline of thelower lip between labrale inferius and soft tissue pogonion

Anatomy of the Skull

Frontal bone: The frontal bone includes a large vertical portion, thesquama frontalis, corresponding to the region known as the forehead.

Mandible: The mandible forms the lower jaw. The mental protuberance isthe bony protuberance of the jaw that forms the chin.

Maxilla: The maxilla forms the upper jaw and is located above themandible and below the orbits. The frontal process of the maxillaprojects upwards by the side of the nose, and forms part of its lateralboundary.

Nasal bones: The nasal bones are two small oblong bones, varying in sizeand form in different individuals; they are placed side by side at themiddle and upper part of the face, and form, by their junction, the“bridge” of the nose.

Nasion: The intersection of the frontal bone and the two nasal bones, adepressed area directly between the eyes and superior to the bridge ofthe nose.

Occipital bone: The occipital bone is situated at the back and lowerpart of the cranium. It includes an oval aperture, the foramen magnum,through which the cranial cavity communicates with the vertebral canal.The curved plate behind the foramen magnum is the squama occipitalis.

Orbit: The bony cavity in the skull to contain the eyeball.

Parietal bones: The parietal bones are the bones that, when joinedtogether, form the roof and sides of the cranium.

Temporal bones: The temporal bones are situated on the bases and sidesof the skull, and support that part of the face known as the temple.

Zygomatic bones: The face includes two zygomatic bones, located in theupper and lateral parts of the face and forming the prominence of thecheek.

Anatomy of the Respiratory System

Diaphragm: A sheet of muscle that extends across the bottom of the ribcage. The diaphragm separates the thoracic cavity, containing the heart,lungs and ribs, from the abdominal cavity. As the diaphragm contractsthe volume of the thoracic cavity increases and air is drawn into thelungs.

Larynx: The larynx, or voice box houses the vocal folds and connects theinferior part of the pharynx (hypopharynx) with the trachea.

Lungs: The organs of respiration in humans. The conducting zone of thelungs contains the trachea, the bronchi, the bronchioles, and theterminal bronchioles. The respiratory zone contains the respiratorybronchioles, the alveolar ducts, and the alveoli.

Nasal cavity: The nasal cavity (or nasal fossa) is a large air filledspace above and behind the nose in the middle of the face. The nasalcavity is divided in two by a vertical fin called the nasal septum. Onthe sides of the nasal cavity are three horizontal outgrowths callednasal conchae (singular “concha”) or turbinates. To the front of thenasal cavity is the nose, while the back blends, via the choanae, intothe nasopharynx.

Pharynx: The part of the throat situated immediately inferior to (below)the nasal cavity, and superior to the oesophagus and larynx. The pharynxis conventionally divided into three sections: the nasopharynx(epipharynx) (the nasal part of the pharynx), the oropharynx(mesopharynx) (the oral part of the pharynx), and the laryngopharynx(hypopharynx).

Materials

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, a preferred form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45 as measured using ASTMD2240

Polycarbonate: a typically transparent thermoplastic polymer ofBisphenol-A Carbonate.

Aspects of a Patient Interface

Anti-asphyxia valve (AAV): The component or sub-assembly of a masksystem that, by opening to atmosphere in a failsafe manner, reduces therisk of excessive CO₂ rebreathing by a patient.

Elbow: A conduit that directs an axis of flow of air to change directionthrough an angle. In one form, the angle may be approximately 90degrees. In another form, the angle may be less than 90 degrees. Theconduit may have an approximately circular cross-section. In anotherform the conduit may have an oval or rectangular cross-section.

Frame: Frame will be taken to mean a mask structure that bears the loadof tension between two or more points of connection with a positioningand stabilising structure. A mask frame may be a non-airtight loadbearing structure in the mask. However, some forms of mask frame mayalso be air-tight.

Positioning and stabilising structure: Positioning and stabilisingstructure will be taken to mean a form of positioning and stabilizingstructure designed for use on a head. Preferably the positioning andstabilising structure comprises a collection of one or more struts, tiesand stiffeners configured to locate and retain a patient interface inposition on a patient's face for delivery of respiratory therapy. Someties are formed of a soft, flexible, elastic material such as alaminated composite of foam and fabric.

Membrane: Membrane will be taken to mean a typically thin element thathas, preferably, substantially no resistance to bending, but hasresistance to being stretched.

Plenum chamber: a mask plenum chamber will be taken to a mean portion ofa patient interface having walls enclosing a volume of space, the volumehaving air therein pressurised above atmospheric pressure in use. Ashell may form part of the walls of a mask plenum chamber. In one form,a region of the patient's face forms one of the walls of the plenumchamber.

Seal: The noun form (“a seal”) will be taken to mean a structure orbarrier that intentionally resists the flow of air through the interfaceof two surfaces. The verb form (“to seal”) will be taken to mean toresist a flow of air.

Shell: A shell will preferably be taken to mean a curved structurehaving bending, tensile and compressive stiffness, for example, aportion of a mask that forms a curved structural wall of the mask.Preferably, compared to its overall dimensions it is relatively thin. Insome forms, a shell may be faceted. Preferably such walls are airtight,although in some forms they may not be airtight.

Stiffener: A stiffener will be taken to mean a structural componentdesigned to increase the bending resistance of another component in atleast one direction.

Strut: A strut will be taken to be a structural component designed toincrease the compression resistance of another component in at least onedirection.

Swivel: (noun) A subassembly of components configured to rotate about acommon axis, preferably independently, preferably under low torque. Inone form, the swivel may be constructed to rotate through an angle of atleast 360 degrees. In another form, the swivel may be constructed torotate through an angle less than 360 degrees. When used in the contextof an air delivery conduit, the sub-assembly of components preferablycomprises a matched pair of cylindrical conduits. Preferably there islittle or no leak flow of air from the swivel in use.

Tie: A tie will be taken to be a structural component designed to resisttension.

Vent: (noun) the structure that allows a deliberate controlled rate leakof air from an interior of the mask, or conduit to ambient air, to allowwashout of exhaled carbon dioxide (CO₂) and supply of oxygen (O₂).

Terms Used in Relation to Patient Interface

Curvature (of a surface): A region of a surface having a saddle shape,which curves up in one direction and curves down in a differentdirection, will be said to have a negative curvature. A region of asurface having a dome shape, which curves the same way in two principledirections, will be said to have a positive curvature. A flat surfacewill be taken to have zero curvature.

Floppy: A quality of a material, structure or composite that is thecombination of features of:

Readily conforming to finger pressure.

Unable to retain its shape when caused to support its own weight.

Not rigid.

Able to be stretched or bent elastically with little effort.

The quality of being floppy may have an associated direction, hence aparticular material, structure or composite may be floppy in a firstdirection, but stiff or rigid in a second direction, for example asecond direction that is orthogonal to the first direction.

Resilient: Able to deform substantially elastically, and to releasesubstantially all of the energy upon unloading, within a relativelyshort period of time such as 1 second.

Rigid: Not readily deforming to finger pressure, and/or the tensions orloads typically encountered when setting up and maintaining a patientinterface in sealing relationship with an entrance to a patient'sairways.

Semi-rigid: means being sufficiently rigid to not substantially distortunder the effects of mechanical forces typically applied during positiveairway pressure therapy.

Other Remarks

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it. It shouldbe further understood that any and all stated values may be variable byup 10-20% from the value stated.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being preferably used toconstruct a component, obvious alternative materials with similarproperties may be used as a substitute. Furthermore, unless specified tothe contrary, any and all components herein described are understood tobe capable of being manufactured and, as such, may be manufacturedtogether or separately.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated by reference todisclose and describe the methods and/or materials which are the subjectof those publications. The publications discussed herein are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing herein is to be construed as an admission that thepresent technology is not entitled to antedate such publication byvirtue of prior invention. Further, the dates of publication providedmay be different from the actual publication dates, which may need to beindependently confirmed.

Moreover, in interpreting the disclosure, all terms should beinterpreted in the broadest reasonable manner consistent with thecontext. In particular, the terms “comprises” and “comprising” should beinterpreted as referring to elements, components, or steps in anon-exclusive manner, indicating that the referenced elements,components, or steps may be present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative examples and that other arrangements may be devisedwithout departing from the spirit and scope of the technology.

REFERENCE SIGNS LIST

-   weft knit fabric 64-   textile 65-   airflow meter 66-   cutting tool 67-   staking punch 68-   laser cutter 69-   mold 70-   molding machine 71-   vent portion 72-   vent portion 73-   acute corner of vent portion 74-   acute corner of vent portion 75-   longer side of vent portion 76-   obtuse corner of vent portion 77-   peripheral edge region of vent portion 78-   central region of vent portion 79-   vertically oriented fibers 80-   loose ends 81-   horizontally oriented fibers 82-   voids 83-   notional left side vent portion 84-   course 85-   basic closed loop warp knit 90-   weft knit 100-   rear portion 210-   straps 220-   patient 1000-   bed partner 1100-   top portion of knitted strap 1102-   rear portion of knitted strap 1104-   knitted strap 1105-   lower portion of knitted strap 1106-   connector 1120-   course 1150-   strap 1200-   course 1250-   connected links 2802-   flexible 3D printed textile 2804-   positioning and stabilising structure piece 2900-   textile 2904-   hole 2912(1)-   female clips 2912-   female clips 2914-   hole 2914(1)-   holes of rigidiser arm 2922-   3D printed strap 2924-   patient interface 3000-   seal-forming structure 3100-   nasal flange 3101-   sealing flange 3110-   support flange 3120-   nasal pillows 3130-   most posterior portion 3130.1-   frusto-cone 3140-   upper flexible region 3142-   stalk 3150-   flexible region 3152-   plenum chamber 3200-   connection portion 3202-   anterior wall 3210-   tongue portion 3211-   channel portion 3211.1-   posterior wall 3220-   posterior surface 3222-   flexing region 3230-   left flexing region 3232-   right flexing region 3234-   decoupling region 3236-   plenum connection region 3240-   retaining structure 3242-   wide retention feature 3244-   narrow retention feature 3245-   barb 3246-   leading surface 3246.1-   trailing surface 3246.2-   additional surface 3246.3-   nominal vertical axis 3246.4-   sealing lip 3250-   pad printing 3290-   embossed text 3291-   recessed text 3292-   pad printing 3293-   ribs 3294-   notches 3295-   positioning and stabilising structure 3300-   strap 3301-   rigidiser arm 3302-   distal free end 3302.1-   button-hole 3303-   flexible joint 3305-   protruding end 3306-   sharp bend 3307-   opening 3308-   protrusion 3309-   frame 3310-   pocketed end 3311-   welded end 3311.1-   wide frame connection region 3312-   lead-in surface 3312.1-   retaining surface 3312.2-   narrow frame connection region 3313-   welded end 3313.1-   interfering portion 3314-   right side strap portion 3315-   left side strap portion 3316-   back strap 3317-   back strap portion 3317 a-   back strap portion 3317 b-   inner side of protrusion 3318-   outer side of protrusion 3319-   end of rigidiser arm 3319 a-   end of rigidiser arm 3319 b-   void of protrusion 3320-   top side of protrusion 3321-   marks 3321 a to 3321 d-   bottom side of protrusion 3322-   curved profile of rigidiser arm 3323-   marks 3323 a to 3323 e-   bifurcation point 3324-   reinforced portion 3325-   split region 3326-   reinforcement portion 3327-   rounded corners 3328-   recess of rigidiser arm 3329-   main section of rigidiser arm 3333-   opening of frame 3335-   extension 3350-   straight section of extension 3351-   bend of extension 3352-   hook of extension 3353-   enclosable section of extension 3354-   outer surface of extension 3355-   joint 3356-   strap logo 3357-   indicia 3358-   flange 3359-   stem 3361-   first section of extension 3363-   second section of extension 3364-   first protrusion of second section 3365-   second protrusion of second section 3366-   first slot of second section 3367-   second slot of second section 3368-   vent 3400-   connection port 3600-   PAP device 4000-   external housing 4010-   upper portion of the external housing 4012-   lower portion of the external housing 4014-   panel 4015-   chassis 4016-   handle 4018-   pneumatic block 4020-   pneumatic components 4100-   inlet air filter 4112-   controllable blower 4142-   air circuit 4170-   web of material 4172-   helical coil 4174-   inner portion of the bend 4176-   long tube 4178-   outer portion of the bend 4179-   short tube 4180-   humped portion 4181-   peak of the fold 4182-   slanted portion 4183-   outer surface of the helical coil 4184-   supplemental oxygen port 4185-   fold line 4186-   rotatable adapter 4190-   electrical components 4200-   printed circuit assembly (PCBA) 4202-   electrical power supply 4210-   input device 4220-   humidifier 5000

PATENT LITERATURE

U.S. Pat. No. 7,743,767; U.S. Pat. No. 7,318,437; US patent publication2009/0044808; WO publication 2000/069521; U.S. Pat. No. 5,724,965; U.S.Pat. No. 6,119,694. U.S. Pat. No. 6,823,869; US patent publication2009/0044808; WO publication 2009/052560; WO publication 2005/010608;U.S. Pat. No. 4,782,832; WO publication 2002/11804; U.S. Pat. No.6,854,465; US publication 2010/0000543; US publication 2009/0107508; WOpublication 2011/121466; U.S. Pat. No. 7,562,658; EP patent 2,022,528;EP 1356841; US publication 2012/0318270; U.S. Pat. No. 8,439,038; US2009/0078259; US publication 2009/0277525; US publication 2010/0224276;U.S. Pat. No. 6,581,594; US publication 2009/0050156; US2010/0319700; USpublication 2009/0044810

1-20. (canceled)
 21. A patient interface system for providingpressurized breathable gas to a patient's airways to provide ContinuousPositive Airway Pressure (CPAP) therapy to a patient for treatment ofsleep disordered breathing (SDB), the patient interface systemcomprising: a patient interface including a seal-forming structure and amask frame; and a positioning and stabilising structure configured toretain the patient interface on the patient's face during therapy, thepositioning and stabilising structure comprising: a strap made of anelastic, textile material, the strap having a first free end and asecond free end; and a first rigidiser arm and a second rigidiser arm,each of the first rigidiser arm and the second rigidiser arm having adistal end located opposite the mask frame and a proximal end that isjoined to the mask frame; wherein the first free end and the second freeend of the strap encloses and abuts a portion of a corresponding one ofthe first rigidiser arm and the second rigidiser arm to limit movementof the strap relative to the corresponding one of the first rigidiserarm and the second rigidiser arm, and wherein the strap is adjustable tofit a range of head sizes by stretching a portion of the strap over thedistal end of the corresponding one of the first rigidiser arm and thesecond rigidiser arm.
 22. A patient interface system according to claim21, wherein the first free end and the second free end of the strap eachcomprises a pocket or a sleeve opening.
 23. A patient interface systemaccording to claim 21, wherein each of the first rigidiser arm and thesecond rigidiser arm is multi-axially deformable to conform to apatient's facial profile.
 24. A patient interface system according toclaim 23, wherein each of the first rigidiser arm and the secondrigidiser arm is shaped to extend from the mask frame to a positionproximally on or below the patient's cheekbone.
 25. A patient interfacesystem according to claim 24, wherein each of the first rigidiser armand the second rigidiser arm has a side profile that is crescent shaped.26. A patient interface system according to claim 21, wherein the strapis substantially free to move by elastically expanding and/orcontracting, relative to the corresponding one of the first rigidiserarm and the second rigidiser arm, and along a longitudinal axis of thestrap.
 27. A patient interface system according to claim 21, wherein theelastic, textile material is any one from the group consisting of:elastane, TPE, nylon and silicone.
 28. A patient interface systemaccording to claim 21, wherein the positioning and stabilising structureis able to stretch along its substantially entire length.
 29. A patientinterface system according to claim 21, wherein the strap is furthercomprises a sleeve arranged to slip over each of the first rigidiser armand the second rigidiser arm such that the strap maintains itssubstantially entire stretchable length and is able to substantiallyfreely stretch over each of the first rigidiser arm and the secondrigidiser arm.
 30. A patient interface system according to claim 29,wherein the sleeve and each of the first rigidiser arm and the secondrigidiser arm are arranged to allow each of the first rigidiser arm andthe second rigidiser arm to move substantially axially inside thesleeve.
 31. A patient interface system according to claim 21, whereineach of the first rigidiser arm and the second rigidiser arm isincapable of stretching and is relatively more rigid than the strap. 32.A patient interface system according to claim 21, wherein the elastic,textile material of the strap further comprises any one from the groupconsisting of: woven, knitted, braided, molded, and extruded.
 33. Apatient interface system according to claim 21, each of the firstrigidiser arm and the second rigidiser arm is symmetrically disposed ona corresponding lateral side of the patient's face.
 34. A patientinterface system according to claim 21, wherein t each of the firstrigidiser arm and the second rigidiser arm is completely removable fromthe strap.
 35. A patient interface system according to claim 21, whereinthe strap includes two side strap portions configured to extend along acorresponding lateral side of the patient's head and each of the twoside strap portions comprises a corresponding one of the first free endand the second free end, and wherein the strap includes two back strapportions arranged to extend along the back of the patient's head.
 36. Apatient interface system according to claim 35, wherein the two backstrap portions comprise a first back strap portion adapted to engage apatient proximal to the crown of the head of the patient and a secondback strap portion adapted to engage the patient proximal to the rear ofthe head.
 37. A patient interface system according to claim 35, whereineach of the two back strap portions are adapted to retain the patientinterface against the nose of the patient with substantially equaltension forces on each of the two back strap portions.
 38. A patientinterface system according to claim 35, wherein when donned by apatient, each of the two back strap portions are in tension with asubstantially equal force.
 39. A patient interface system according toclaim 35, wherein each of the two back strap portions arenon-independently adjustable such that the two back strap portionsnaturally center on respective sides of the crown of the head of apatient.
 40. A patient interface system according to claim 39, whereinthe two back strap portions are symmetrical.
 41. A patient interfacesystem according to claim 35, wherein a split region is defined betweenthe two back strap portions and the split region is approximately 200 mmin length.